Ink for inkjet recording, inkjet recording method, and printed matter

Abstract

The present invention provides an ink for inkjet recording, which contains at least one infrared absorbing dye (A) selected from the group consisting of a dye A1 represented by formula (1) and a dye multimer A2 that contains two or more dye structures derived from the dye A1 in one molecule. The invention provides an ink jet recording method and a printed matter using an ink for ink jet recording. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to an inkjet recording ink containing an infrared absorbing pigment, and also to an inkjet recording method and a printed matter using the inkjet recording ink. Background Art

[0002] Usually, as an institution for optically reading information recorded on bills such as stocks, bonds, checks, commodity certificates, lottery tickets, and regular tickets, most of them are provided with a readable coding pattern using a barcode or an optical character reader (OCR). In addition, as a coding pattern using optical reading, a barcode is widely used mainly in logistics management systems, etc. Moreover, in recent years, two-dimensional codes such as VeriCode, Code One, Maxi Code, and two-dimensional barcodes (QR Code (registered trademark)) with larger data capacity and high-density printing are also popularized. In addition, a method using a dot pattern is also known.

[0003] The above-mentioned coding pattern is usually a visible coding pattern, which imposes various restrictions on the design of the printed matter and the securing of the printing area, and therefore, there is an increasing demand to resolve these restrictions. In addition, for the purpose of anti-counterfeiting of bills, attempts have been made to make the coding pattern transparent by printing ink that does not have an absorption band in the visible light region. By making the coding pattern transparent, there are advantages such as freedom in the design of the printed matter, no need to secure the printing area for printing the coding pattern, and difficulty in visually judging and identifying the coding pattern.

[0004] As an attempt to make it transparent (invisible), it is known that an infrared absorption pattern is formed using ink that mainly absorbs infrared rays outside the visible light region. Ink containing an infrared absorption pigment is used as such ink (Patent Document 1, etc.).

[0005] Previous technical literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 11-282136 Summary of the invention

[0008] Technical issues to be solved by the invention

[0009] Inkjet recording inks are required to have excellent storage stability from the viewpoint of ejection properties, etc. In recent years, there has been a demand for further improvement in storage stability.

[0010] Therefore, an object of the present invention is to provide an inkjet recording ink having excellent storage stability. In addition, the present invention is to provide an inkjet recording method and a printed matter.

[0011] Means for solving technical problems

[0012] The present invention provides the following contents.

[0013] <1> An inkjet recording ink comprising at least one infrared absorbing dye A selected from a dye A1 represented by formula (1) and a dye multimer A2 containing two or more dye structures derived from the dye A1 in one molecule;

[0014] [Chemical formula 1]

[0015]

[0016] In formula (1), L 101 Represents -P(=O)(R L101 )-、-P(=S)(R L102 )-、-Si(R L103 )(R L104 )-、-B(R L105 )-, -S(=O)2- or -S(=O)-, R L101 ~R L105 Each independently represents a hydrogen atom or a substituent, R L103 With R L104 can bond to form a ring,

[0017] X 101 ~X 103 Each independently represents a nitrogen atom or -CR X101 -, R X101 represents a hydrogen atom or a substituent,

[0018] L 102 and L 103 Each independently represents a sulfur atom or -X 104 =X 105 -, X 104 and X 105 Each independently represents a nitrogen atom or -CR X102 -, R X102 represents a hydrogen atom or a substituent,

[0019] Ar 101 and Ar 102 Respectively independently represent -(CR Ar101 =CR Ar102 ) n101 -, an arylene group, a heterocyclic group or a group formed by combining two or more of these groups, R Ar101 and R Ar102 Each independently represents a hydrogen atom or a substituent, n101 represents an integer of 1 to 3,

[0020] Y101 and Y 102 Represents -OR independently Y101 、-NR Y102 R Y103 or -SR Y104 , R Y101 ~R Y104 Each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heteroaryl group, and R Y102 With R Y103 They may be bonded via a single bond or a divalent linking group to form a ring,

[0021] Ar 101 With X 101 They may be bonded via a single bond or a divalent linking group to form a 5-membered ring or a 6-membered ring.

[0022] Ar 101 With Y 101 They may be bonded via a single bond or a divalent linking group to form a 5-membered ring or a 6-membered ring.

[0023] Ar 102 With X 102 They may be bonded via a single bond or a divalent linking group to form a 5-membered ring or a 6-membered ring.

[0024] Ar 102 With Y 102 They may be bonded via a single bond or a divalent linking group to form a 5-membered ring or a 6-membered ring.

[0025] Z 1 represents the counter ion,

[0026] p1 represents an integer from 0 to 5,

[0027] q1 represents an integer from 1 to 5.

[0028] <2> according to <1> The ink for inkjet recording, wherein:

[0029] X in the above formula (1) 103 For-CR X101 -, R X101 is a hydrogen atom or a substituent,

[0030] L 102 and L 103 are sulfur atoms respectively.

[0031] <3> according to <1> The ink for inkjet recording, wherein:

[0032] X in the above formula (1) 103 For-CR X101 -, R X101 is a hydrogen atom or a substituent,

[0033] L 102 and L 103 are sulfur atoms,

[0034] L 101 =P(=O)(R L101 )-, R L101 is a hydrogen atom or a substituent.

[0035] <4> according to <1> The ink for inkjet recording, wherein:

[0036] X in the above formula (1) 103 For-CR X101 -, R X101 is a hydrogen atom or a substituent,

[0037] L 102 and L 103 are sulfur atoms,

[0038] L 101 =P(=O)(R L101 )-, R L101 is a hydrogen atom or a substituent,

[0039] Y 101 and Y 102 Each independently is -NR Y102 R Y103 , R Y102 and R Y103 are independently a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heteroaryl group, R Y102 With R Y103 They may be bonded via a single bond or a divalent linking group to form a ring.

[0040] <5> according to <1> The ink for inkjet recording, wherein:

[0041] X in the above formula (1) 103 For-CR X101 -, R X101 is a hydrogen atom or a substituent,

[0042] L 102 and L 103 are sulfur atoms,

[0043] L 101 -Si(R L103 )(R L104 )- or -S(=O)-,

[0044] R L103 and R L104 are each independently a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heteroaryl group,

[0045] Y 101 and Y 102 Each independently is -NR Y102 R Y103 , R Y102 and R Y103 are independently a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heteroaryl group, R Y102 With R Y103 They may be bonded via a single bond or a divalent linking group to form a ring.

[0046] <6> according to <1> to <5> The inkjet recording ink according to any one of the preceding claims, wherein

[0047] When the inkjet recording ink is dried, the maximum absorption wavelength of the dried product is within a wavelength range of 700 to 1800 nm.

[0048] <7> according to <1> to <6> The inkjet recording ink described in any one of the above aspects contains water and an organic solvent having a boiling point of 100° C. or higher at 101.325 kPa.

[0049] <8> according to <7> The inkjet recording ink further comprises resin particles.

[0050] <9> according to <1> to <6> The inkjet recording ink described in any one of the preceding claims contains a radical polymerizable monomer and a photoradical polymerization initiator.

[0051] <10> according to <9> The ink for inkjet recording further comprises a sensitizer.

[0052] <11> according to <9> or <10> The ink for inkjet recording is a photocurable ink.

[0053] <12> An inkjet recording method comprising using <1> to <11> A step of forming an infrared absorption image using any one of the inkjet recording inks.

[0054] <13> A printed matter, comprising:

[0055] substrate; and

[0056] use <1> to <11> An infrared absorption image obtained using any one of the inkjet recording inks.

[0057] Effects of the Invention

[0058] According to the present invention, it is possible to provide an inkjet recording ink having excellent storage stability, and also to provide an inkjet recording method and a printed matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 It is a schematic plan view showing an example of the arrangement of dot patterns in one first grid. DETAILED DESCRIPTION

[0060] Hereinafter, the contents of the present invention will be described in detail.

[0061] In this specification, "to" is used to mean that the numerical values ​​described before and after it are included as the lower limit and the upper limit.

[0062] In the description of groups (atomic groups) in this specification, the description not marked with substituted or unsubstituted includes groups (atomic groups) without substitution and also includes groups (atomic groups) with substitution. For example, "alkyl" includes not only alkyl groups without substitution (unsubstituted alkyl groups) but also alkyl groups with substitution (substituted alkyl groups).

[0063] In the present specification, “(meth)acrylate” means both or either acrylate and methacrylate, “(meth)acrylic acid” means both or either acrylic acid and methacrylic acid, and “(meth)acryloyl” means both or either acryloyl and methacryloyl.

[0064] In this specification, infrared rays refer to light (electromagnetic waves) with a wavelength of 700 to 2500 nm.

[0065] In the present specification, the term "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes as long as the intended effect of the process is achieved.

[0066] <Inkjet Recording Ink>

[0067] The inkjet recording ink of the present invention is characterized by comprising at least one infrared absorbing dye A selected from a dye A1 represented by formula (1) and a dye multimer A2 containing two or more dye structures derived from the dye A1 in one molecule.

[0068] About the infrared absorption pigment A included in the ink for inkjet recording of the present invention, although the detailed reason is unclear, the dispersibility in the ink is good, and it is difficult to produce coarse particles.Therefore, the storage stability of the ink for inkjet recording of the present invention is excellent.Therefore, according to the ink for inkjet recording of the present invention, when forming an image by inkjet method, the generation of nozzle clogging etc. can be suppressed.

[0069] Furthermore, since the infrared absorbing dye A is excellent in infrared shielding properties and visible transparency, an image that is invisible and has excellent readability by a detector using infrared light can be formed by using the inkjet recording ink of the present invention.

[0070] When the inkjet recording ink of the present invention is dried, the maximum absorption wavelength of the dried product is preferably within a wavelength range of 700 to 1800 nm, more preferably within a wavelength range of 800 to 1600 nm, and even more preferably within a wavelength range of 900 to 1600 nm.

[0071] In this specification, the dried product of the inkjet recording ink is prepared by mixing the inkjet recording ink at 0.20 g / m 2 The product was sprayed onto OK Top Coat paper (manufactured by OJI PAPER CO., LTD.) and dried naturally at 25°C and 55% relative humidity for 24 hours. The maximum absorption wavelength when dried was determined by measuring the reflection spectrum using a spectrophotometer UV-3100PC (manufactured by Shimadzu Corporation) equipped with a large integrating sphere attachment LISR-3100 (manufactured by Shimadzu Corporation) with a diameter of 150 mm.

[0072] In the inkjet recording ink of the present invention, the maximum absorption wavelength in the range of 400 nm to 1800 nm when dried is preferably within the range of 700 to 1800 nm from the viewpoint of invisibility and readability of the infrared absorption image obtained.

[0073] The value of the maximum absorption wavelength can be determined by measuring the optical density in the wavelength range of 400 nm to 1800 nm in the same manner as the determination of the maximum absorption wavelength when the dried product is prepared. The optical density was determined using a spectrophotometer UV-3100PC (manufactured by Shimadzu Corporation) equipped with a large integrating sphere attachment LISR-3100 (manufactured by Shimadzu Corporation) with a diameter of 150 mm.

[0074] In the inkjet recording ink of the present invention, the optical density at a wavelength of 450 nm when dried is preferably 1 / 5 or less of the optical density at the maximum absorption wavelength from the viewpoint of invisibility of the infrared absorption image obtained.

[0075] From the viewpoint of readability, the optical density of the dried product at the maximum absorption wavelength is preferably 0.1 or more, more preferably 0.3 or more, and even more preferably 0.5 or more.

[0076] The maximum value of the optical density of the dried product at a wavelength of 400 to 700 nm is preferably 0.5 or less.

[0077] Hereinafter, each component used in the inkjet recording ink of the present invention will be described.

[0078] 《Specific infrared absorbing pigments》

[0079] The inkjet recording ink of the present invention contains at least one infrared absorbing dye A selected from the group consisting of a dye A1 represented by formula (1) and a dye multimer A2 containing two or more dye structures derived from the dye A1 in one molecule. Hereinafter, the infrared absorbing dye is also referred to as a specific infrared absorbing dye.

[0080] The specific infrared absorbing dye may be a dye or a pigment.

[0081] When the specific infrared absorbing pigment is a pigment, the solubility of the specific infrared absorbing pigment in either propylene glycol monomethyl ether acetate or water at 25°C is preferably 0.1g / 100g or less. Furthermore, when the specific infrared absorbing pigment is a pigment, the average particle size of the pigment is preferably 20 to 300nm, more preferably 25 to 250nm, and further preferably 30 to 200nm. The "average particle size" mentioned herein represents the average particle size of the secondary particles formed by the aggregation of the primary particles of the pigment. Furthermore, the particle size distribution of the secondary particles of the pigment (hereinafter also referred to as "particle size distribution") is preferably that the secondary particles entering (average particle size ± 100) nm are more than 70% by mass of the whole, preferably more than 80% by mass. In addition, the particle size distribution of the secondary particles can be measured using the scattering intensity distribution.

[0082] -Pigment A1-

[0083] First, the dye A1 represented by formula (1) will be described.

[0084] [Chemical formula 2]

[0085]

[0086] L in formula (1) 101 Represents -P(=O)(R L101 )-、-P(=S)(R L102 )-、-Si(R L103 )(R L104 )-、-B(R L105 )-, -S(=O)2- or -S(=O)-, R L101 ~R L105 Each independently represents a hydrogen atom or a substituent.

[0087] As R L101 ~R L105The substituent represented by may include alkyl, alkenyl, alkynyl, aryl, heteroaryl, alkoxy, aryloxy and alkenyloxy, preferably alkyl or aryl, more preferably aryl. These groups may also have a substituent. As the substituent, the groups listed in the substituent T described later and the groups containing anions described later may be mentioned.

[0088] The number of carbon atoms in the alkyl group is preferably 1 to 10, more preferably 1 to 6, and even more preferably 1 to 4. The alkyl group may be linear, branched, or cyclic.

[0089] The number of carbon atoms in the alkenyl group is preferably 2 to 10, more preferably 2 to 6, and even more preferably 2 to 4. The alkenyl group may be either linear or branched.

[0090] The number of carbon atoms in the alkynyl group is preferably 2 to 10, more preferably 2 to 6, and even more preferably 2 to 4. The alkynyl group may be either linear or branched.

[0091] The number of carbon atoms in the aryl group is preferably 6 to 20, more preferably 6 to 12. Furthermore, the aryl group is preferably a monocyclic aryl group.

[0092] The heteroaryl group is preferably a 5-membered ring or a 6-membered ring. The heteroatom constituting the ring of the heteroaryl group is preferably an oxygen atom, a nitrogen atom, and a sulfur atom. The number of heteroatoms constituting the ring of the heteroaryl group is preferably 1 to 3.

[0093] The number of carbon atoms in the alkoxy group is preferably 1 to 10, more preferably 1 to 6, and even more preferably 1 to 4. The alkoxy group may be either a linear chain or a branched chain.

[0094] The aryloxy group has preferably 6 to 20 carbon atoms, more preferably 6 to 12 carbon atoms.

[0095] The number of carbon atoms of the alkenyloxy group is preferably 1 to 10, more preferably 1 to 6, and even more preferably 1 to 4. The alkenyloxy group may be either linear or branched.

[0096] From the reason that the maximum absorption wavelength can be further increased and the light resistance can be further improved, L in formula (1) 101 Preferably -P(=O)(R L101 )-.

[0097] L in formula (1) 101 -Si(R L103 )(R L104 )- or -S(=O)-.

[0098] X in formula (1) 101 ~X 103 Each independently represents a nitrogen atom or -CR X101 -, R X101 represents a hydrogen atom or a substituent.X101 The substituent represented may include the groups listed in the substituent T described later, preferably a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heteroaryl group, a hydroxyl group, an alkoxy group, an aryloxy group, an alkenyloxy group or an amino group. These groups may also have a substituent. As a substituent, the groups listed in the substituent T described later, the groups containing anions described later, the groups containing ethylenically unsaturated bonds, etc. may be mentioned. As the groups containing ethylenically unsaturated bonds, vinyl, (meth) allyl, (meth) acryloyl, etc. may be mentioned.

[0099] The number of carbon atoms in the alkyl group is preferably 1 to 10, more preferably 1 to 6, and even more preferably 1 to 4. The alkyl group may be linear, branched, or cyclic.

[0100] The number of carbon atoms in the alkenyl group is preferably 2 to 10, more preferably 2 to 6, and even more preferably 2 to 4. The alkenyl group may be either linear or branched.

[0101] The number of carbon atoms in the alkynyl group is preferably 2 to 10, more preferably 2 to 6, and even more preferably 2 to 4. The alkynyl group may be either linear or branched.

[0102] The number of carbon atoms in the aryl group is preferably 6 to 20, more preferably 6 to 12. Furthermore, the aryl group is preferably a monocyclic aryl group.

[0103] The heteroaryl group is preferably a 5-membered ring or a 6-membered ring. The heteroatom constituting the ring of the heteroaryl group is preferably an oxygen atom, a nitrogen atom, and a sulfur atom. The number of heteroatoms constituting the ring of the heteroaryl group is preferably 1 to 3.

[0104] The number of carbon atoms in the alkoxy group is preferably 1 to 10, more preferably 1 to 6, and even more preferably 1 to 4. The alkoxy group may be either a linear chain or a branched chain.

[0105] The aryloxy group has preferably 6 to 20 carbon atoms, more preferably 6 to 12 carbon atoms.

[0106] The number of carbon atoms of the alkenyloxy group is preferably 1 to 10, more preferably 1 to 6, and even more preferably 1 to 4. The alkenyloxy group may be either linear or branched.

[0107] From the reason that the solubility or visible transparency of the compound can be further improved, R X101 It is preferably an aryl group or a heteroaryl group, more preferably an aryl group, further preferably a monocyclic aryl group, further preferably a monocyclic aryl group having a substituent, and particularly preferably a monocyclic aryl group having a substituent at the ortho position. As the substituent, there can be mentioned the groups listed in the substituent T described later, the groups containing anions described later, the groups containing ethylenically unsaturated bonds, etc., and preferably an alkyl group, a sulfo group, a carboxyl group, a salt of a carboxyl group, a salt of a sulfo group, the groups containing anions described later, or the groups containing ethylenically unsaturated bonds.

[0108] X in formula (1) 101 and X 102 Preferably, each independently is -CR X101 -. And, R X101 Preferred is a hydrogen atom.

[0109] X in formula (1) 103 Preferred is -CR X101 -. And, R X101 It is preferably a substituent, preferably an aryl group or a heteroaryl group, more preferably an aryl group, further preferably a monocyclic aryl group, further preferably a monocyclic aryl group having a substituent, and particularly preferably a monocyclic aryl group having a substituent at the ortho position.

[0110] L in formula (1) 102 and L 103 Each independently represents a sulfur atom or -X 104 =X 105 -, X 104 and X 105 Each independently represents a nitrogen atom or -CR X102 -, R X102 represents a hydrogen atom or a substituent. X102 The substituent represented by may be exemplified as the above R X101 The preferred ranges of the groups explained with reference to the substituents represented by hereinafter are also the same.

[0111] From the reason that the maximum absorption wavelength can be present on the longer wavelength side, L 102 A sulfur atom is preferred.

[0112] From the reason that the maximum absorption wavelength can be present on the longer wavelength side, L 103 A sulfur atom is preferred.

[0113] L 102 and L 103 Particularly preferably, they are each a sulfur atom.

[0114] Ar in formula (1) 101 and Ar 102 Respectively independently represent -(CR Ar101 =CR Ar102 ) n101 -, an arylene group, a heterocyclic group or a group formed by combining two or more of these groups, R Ar101 and R Ar102 Each independently represents a hydrogen atom or a substituent, and n101 represents an integer of 1-3.

[0115] As R Ar101 and R Ar102 The substituent represented by may be exemplified as the above RX101 The preferred ranges of the groups explained with reference to the substituents represented by hereinafter are also the same.

[0116] n101 represents an integer of 1 to 3, preferably 1 or 2, and more preferably 1.

[0117] Ar in formula (1) 101 and Ar 102 The number of carbon atoms of the arylene group represented is preferably 6 to 20, more preferably 6 to 12. Furthermore, the arylene group is preferably a monocyclic arylene group.

[0118] Ar in formula (1) 101 and Ar 102 The heterocyclic group represented by is preferably a 5-membered ring or a 6-membered ring. The heteroatom constituting the ring of the heterocyclic group is preferably an oxygen atom, a nitrogen atom and a sulfur atom. The number of heteroatoms constituting the ring of the heterocyclic group is preferably 1 to 3.

[0119] Ar in formula (1) 101 and Ar 102 Preferably, each independently is -(CR Ar101 =CR Ar102 ) n101 -, arylene group or a group formed by combining these.

[0120] As a preferred embodiment, Ar 101 and Ar 102 Each independently represents an arylene group.

[0121] As another preferred embodiment, Ar 101 and Ar 102 Each independently Ar101 =CR Ar102 ) n101 - and arylene groups. Ar101 =CR Ar102 ) n101 The group formed by combining - and an arylene group is preferably - *1 -(CR Ar101 =CR Ar102 ) n101 -Arylene- *2 .and, *2 Preferably, Y of formula (1) 101 or Y 102 The bonding key.

[0122] Y in formula (1) 101 and Y 102 Represents -OR independently Y101 、-NR Y102 R Y103 or -SRY104 , R Y101 ~R Y104 Each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heteroaryl group, and R Y102 With R Y103 They may be bonded via a single bond or a divalent linking group to form a ring.

[0123] R Y101 ~R Y104 Preferably, each is independently an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heteroaryl group, more preferably an alkyl group or an aryl group, and further preferably an aryl group.

[0124] R Y101 ~R Y104 The number of carbon atoms of the alkyl group represented is preferably 1 to 10, more preferably 1 to 6, and further preferably 1 to 4. The alkyl group may be any of a linear, branched, and cyclic group. The alkyl group may further have a substituent. As the substituent, there may be mentioned the groups listed in the substituent T described later, the groups containing anions described later, the groups containing ethylenically unsaturated bonds, and the like.

[0125] R Y101 ~R Y104 The number of carbon atoms of the alkenyl group represented is preferably 2 to 10, more preferably 2 to 6, and further preferably 2 to 4. The alkenyl group may be any of a straight chain and a branched chain. The alkenyl group may further have a substituent. As the substituent, there may be mentioned the groups listed in the substituent T described later, the groups containing anions described later, the groups containing ethylenic unsaturated bonds, and the like.

[0126] R Y101 ~R Y104 The number of carbon atoms of the alkynyl group represented is preferably 2 to 10, more preferably 2 to 6, and further preferably 2 to 4. The alkynyl group may be any of a straight chain and a branched chain. The alkynyl group may further have a substituent. As the substituent, there may be mentioned the groups listed in the substituent T described later, the groups containing anions described later, the groups containing ethylenically unsaturated bonds, and the like.

[0127] R Y101 ~R Y104 The number of carbon atoms of the aryl group represented is preferably 6 to 20, more preferably 6 to 12. In addition, the aryl group is preferably a monocyclic aryl group. The aryl group may further have a substituent. As the substituent, there may be mentioned the groups listed in the substituent T described later, the groups containing anions described later, the groups containing ethylenically unsaturated bonds, etc.

[0128] R Y101 ~R Y104The heteroaryl represented is preferably a 5-membered ring or a 6-membered ring. The heteroatoms constituting the ring of the heteroaryl are preferably oxygen atoms, nitrogen atoms and sulfur atoms. The number of heteroatoms constituting the ring of the heteroaryl is preferably 1 to 3. The heteroaryl group may further have a substituent. As the substituent, the groups listed in the substituent T described later, the groups containing anions described later, the groups containing ethylenically unsaturated bonds, etc. may be mentioned.

[0129] -NR Y102 R Y103 R Y102 and R Y103 The ring may be formed by bonding via a single bond or a divalent linking group. Examples of the divalent linking group include -CR Y111 R Y112 , -O-, -S-, and groups formed by combining two or more of these. Y111 and R Y112 Each independently represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group or a heteroaryl group. These groups may also have a substituent. As a substituent, the groups listed in the substituent T described later, the groups containing anions described later, the groups containing ethylenic unsaturated bonds, etc. can be cited.

[0130] Y in formula (1) 101 and Y 102 Preferably, each independently is -NR Y102 R Y103 .

[0131] In formula (1), Ar 101 and X 101 They may be bonded via a single bond or a divalent linking group to form a 5-membered ring or a 6-membered ring.

[0132] Ar 101 With Y 101 They may be bonded via a single bond or a divalent linking group to form a 5-membered ring or a 6-membered ring.

[0133] Ar 102 With X 102 They may be bonded via a single bond or a divalent linking group to form a 5-membered ring or a 6-membered ring.

[0134] Ar 102 With Y 102 The rings may be bonded via a single bond or a divalent linking group to form a 5-membered ring or a 6-membered ring.

[0135] Examples of the divalent linking group include -CR Y121 R Y122 -, -O-, -S-, and groups formed by combining two or more of these. Y121 and R Y122Each independently represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group or a heteroaryl group. These groups may also have a substituent. As a substituent, the groups listed in the substituent T described later, the groups containing anions described later, the groups containing ethylenic unsaturated bonds, etc. can be cited.

[0136] Z in formula (1) 1 represents a counter ion. Examples of the counter ion include a counter anion and a counter cation.

[0137] The counter cation may be an inorganic cation or an organic cation.

[0138] Examples of inorganic cations include monovalent metal cations such as Na (sodium) cations, Li (lithium) cations, and K (potassium) cations; and divalent or higher metal cations such as Mg (magnesium) cations, Ca (calcium) cations, Sr (strontium) cations, Ba (barium) cations, Ti (titanium) cations, Zr (zirconium) cations, Cr (chromium) cations, Mn (manganese) cations, Fe (iron) cations, Co (cobalt) cations, Ni (nickel) cations, Cu (copper) cations, Zn (zinc) cations, Cd (cadmium) cations, Al (aluminum) cations, In (indium) cations, Sn (tin) cations, Pb (lead) cations, and Bi (bismuth) cations.

[0139] Examples of the organic cation include ammonium cations (tetraalkylammonium cations, trialkylammonium cations, etc.), imidazolium cations, pyridinium cations (pyridinium cations, N-methylpyridinium cations, N-ethylpyridinium cations, etc.), and phosphonium cations.

[0140] From the viewpoint of being able to further improve light resistance and heat resistance, the counter cation is preferably an inorganic cation, and more preferably a Na cation, a Li cation, a K cation, a Mg cation, or a Ba cation.

[0141] The counter anion may be an organic anion or an inorganic anion. As the counter anion, anions represented by formula (AN1), anions represented by formula (AN2), anions represented by formula (AN3), anions represented by formula (AN4), anions represented by formula (AN5), fluoride anions, chloride anions, bromide anions, iodide anions, cyanide anions, perchlorate anions, carboxylate anions, sulfonate anions, phosphate anions, heteropolyacids (phosphotungstic acid, phosphomolybdic acid, phosphotungstomolybdic acid, silicotungstic acid, silicomolybdic acid, silicotungstomolybdic acid, etc.) anions, isopolyacids (tungstic acid, molybdic acid, etc.) anions, etc.

[0142] [Chemical formula 3]

[0143]

[0144] In formula (AN1), R AN1 and R AN2 Each independently represents a halogen atom or an alkyl group, R AN1 With R AN2 can bond to form rings;

[0145] In formula (AN2), R AN3 ~R AN5 Each independently represents a halogen atom or an alkyl group, R AN3 With R AN4 , R AN4 With R AN5 or R AN3 With R AN5 can bond to form rings;

[0146] In formula (AN3), R AN6 ~R AN9 each independently represents a halogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group or a cyano group;

[0147] In formula AN4), R AN10 represents a halogenated hydrocarbon group which may be connected via a connecting group having a nitrogen atom or an oxygen atom;

[0148] In formula AN5), R AN11 ~R AN16 Each independently represents a halogen atom or a halogenated hydrocarbon group.

[0149] As R in formula (AN1) AN1 and R AN2 The halogen atom represented by AN3 ~R AN5 The halogen atom represented by and R AN6 ~R AN9 Examples of the halogen atom represented by include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, and a fluorine atom is preferred.

[0150] R of formula (AN1) AN1 and R AN2 The alkyl represented by the formula AN2) R AN3 ~R AN5 The alkyl represented by and R of formula AN3) AN6 ~R AN9The number of carbon atoms of the alkyl group represented is preferably 1 to 10, more preferably 1 to 6, and further preferably 1 to 3. The alkyl group may be a straight chain, a branched chain, or a cyclic chain, preferably a straight chain or a branched chain, and more preferably a straight chain. The alkyl group may have a substituent or may be unsubstituted. The alkyl group is preferably an alkyl group having a halogen atom as a substituent, and more preferably an alkyl group having a fluorine atom as a substituent (fluoroalkyl group). Furthermore, the fluoroalkyl group is preferably a perfluoroalkyl group.

[0151] R in formula (AN3) AN6 ~R AN9 The number of carbon atoms of the aryl group represented is preferably 6 to 20, more preferably 6 to 12, and further preferably 6. The aryl group may have a substituent or may be unsubstituted. As the substituent, a halogen atom and an alkyl group may be mentioned. As the halogen atom, a fluorine atom is preferred. As the alkyl group, a fluoroalkyl group is preferred.

[0152] R in formula (AN3) AN6 ~R AN9 The number of carbon atoms of the alkoxy group represented is preferably 1 to 10, more preferably 1 to 6, and further preferably 1 to 3. As for the alkoxy group, linear, branched, and cyclic groups can be mentioned, preferably linear or branched, and more preferably linear. The alkoxy group may have a substituent or may be unsubstituted. As the substituent, a halogen atom and an alkyl group can be mentioned. As the halogen atom, a fluorine atom is preferred. As the alkyl group, a fluoroalkyl group is preferred.

[0153] R in formula (AN3) AN6 ~R AN9 The number of carbon atoms of the aryloxy group represented is preferably 6 to 20, more preferably 6 to 12, and further preferably 6. The aryloxy group may have a substituent or may be unsubstituted. Examples of the substituent include a halogen atom and an alkyl group. The halogen atom is preferably a fluorine atom. The alkyl group is preferably a fluoroalkyl group.

[0154] R of formula (AN1) AN1 With R AN2 They may be bonded to form a ring. AN3 With R AN4 , R AN4 With R AN5 or R AN3 With R AN5 They may be bonded to form a ring.

[0155] R of formula (AN4) AN10It represents a halogenated hydrocarbon group that can be connected by a connecting group having a nitrogen atom or an oxygen atom. The halogenated hydrocarbon group refers to a monovalent hydrocarbon group substituted by a halogen atom, preferably a monovalent hydrocarbon group substituted by a fluorine atom. As the hydrocarbon group, an alkyl group, an aryl group, etc. can be mentioned. The monovalent hydrocarbon group substituted by a halogen atom can also have a substituent. As the connecting group having a nitrogen atom or an oxygen atom, -O-, -CO-, -COO-, -CO-NH-, etc. can be mentioned.

[0156] R of formula (AN5) AN11 ~R AN16 Each independently represents a halogen atom or a halogenated hydrocarbon group. As the halogen atom, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom can be mentioned, and a fluorine atom is preferably mentioned. As the halogenated hydrocarbon group, an alkyl group having a halogen atom as a substituent is preferably mentioned, and an alkyl group having a fluorine atom as a substituent is more preferably mentioned.

[0157] Specific examples of heteropolyacid anions and isopolyacid anions include tungstate anions ([W6O 19 ] 2- , [W 10 O 32 ] 4- , [WO4] 2- etc.), molybdate anion ([Mo2O7] 2- 、[Mo6O 19 ] 2- 、[Mo8O 26 ] 4- etc.), phosphotungstate anion ([PW4O 20 ] 4- , [PW 12 O 40 ] 3- 、[P2W 15 O 56 ] 12- 、[P2W 17 O 61 ] 10- 、[P2W 18 O 62 ] 6- etc.), phosphomolybdic acid anion ([P2Mo 18 O 62 ] 6- 、[PMo 12 O 40 ] 3- etc.), phosphotungstomolybdate anion ([PW 12-x Mo x O 40 ] 3- (x is an integer from 1 to 11), [P2W 18-y Mo y O 62] 6- (y is an integer of 1 to 17), silicotungstate anion ([SiW9O 34 ] 10- 、[SiW 10 O 36 ] 8- 、[SiW 11 O 39 ] 8- 、[SiW 12 O 40 ] 4- etc.), silicomolybdate anion ([SiMo 12 O 40 ] 4- etc.), silicotungstomolybdate anion ([SiW 12-x Mo x O 40 ] 4- (x is an integer of 1 to 11), etc.) and tungsten-based isopoly acid anions.

[0158] The counter anion may be a divalent or higher anion. Examples of the divalent or higher anion include anions having two or more monovalent anions such as imide anions, methide anions, borate anions, and sulfonate anions in one molecule.

[0159] In formula (1), p1 represents an integer of 0 to 5, and q1 represents an integer of 1 to 5. p1 is preferably an integer of 0 to 3, more preferably an integer of 0 to 2. q1 is preferably an integer of 1 to 3, more preferably 1 or 2, and further preferably 1.

[0160] When the charge in [ ] in formula (1) is biased toward positive charge, p1 is an integer greater than 1, and Z 1 The counter ion represented by is preferably a counter anion. Furthermore, the product of the valence of the positive charge in [] in formula (1) and q1 is preferably Z 1 The valence of the charge of the counter anion represented is the same value as the product of p1.

[0161] When the charge in [ ] in formula (1) is biased toward negative charge, p1 is an integer greater than 1, and Z 1 The counter ion represented by is preferably a counter cation. In addition, the product of the valence of the negative charge in [] in formula (1) and q1 is preferably Z 1 The valence of the charge of the counter cation represented is the same value as the product of p1.

[0162] When the charges in [] in equation (1) are neutral, Z 1 Preferably, it is absent, ie, p1 is 0 and q1 is 1.

[0163] The dye A1 is also preferably a dye represented by formula (2).

[0164] [Chemical formula 4]

[0165]

[0166] In formula (2), L 201 Represents -P(=O)(R L101 )-、-P(=S)(R L102 )-、-Si(R L103 )(RL 104 )-、-B(RL 105 )-, -S(=O)2- or -S(=0)-, R L101 ~R L105 Each independently represents a hydrogen atom or a substituent, R L103 With R L104 can bond to form a ring,

[0167] R X111 and R X112 each independently represents a hydrogen atom or a substituent,

[0168] X 203 Represents nitrogen atom or -CR X101 -, R X101 represents a hydrogen atom or a substituent,

[0169] L 202 ~L 205 Each independently represents a sulfur atom or -X 104 =X 105 -, X 104 and X 105 Each independently represents a nitrogen atom or -CR X102 -, R X102 represents a hydrogen atom or a substituent,

[0170] Ar 201 and Ar 202 Respectively independently represent -(CR Ar201 =CR Ar202 ) n201 -, an arylene group, a heterocyclic group or a group formed by combining two or more of these groups, R Ar201 and R Ar202 Each independently represents a hydrogen atom or a substituent, n201 represents an integer of 1 to 3,

[0171] Y 201 and Y 202 Represents -OR independently Y101 、-NR Y102 R Y103 or -SR Y104, R Y101 ~R Y104 Each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heteroaryl group, and R Y102 With R Y103 They may be bonded via a single bond or a divalent linking group to form a ring,

[0172] Ar 201 With X 201 They may be bonded via a single bond or a divalent linking group to form a 5-membered ring or a 6-membered ring.

[0173] Ar 201 With Y 201 They may be bonded via a single bond or a divalent linking group to form a 5-membered ring or a 6-membered ring.

[0174] Ar 202 With X 202 They may be bonded via a single bond or a divalent linking group to form a 5-membered ring or a 6-membered ring.

[0175] Ar 202 With Y 202 They may be bonded via a single bond or a divalent linking group to form a 5-membered ring or a 6-membered ring.

[0176] Z 2 represents the counter ion,

[0177] p2 represents an integer from 0 to 5,

[0178] q2 represents an integer from 1 to 5.

[0179] L in formula (2) 201 , L 202 , L 203 , X 203 , Y 201 , Y 202 , Z 2 The meanings of q2 and p2 are the same as those of L in formula (1). 101 , L 102 , L 103 , X 103 , Y 101 , Y 102 , Z 1 , q1, and p1 have the same meanings and the same preferred ranges.

[0180] Regarding R in formula (2) X111 and R X112 The substituent represented by may be exemplified as R in formula (1): X101 The preferred ranges of the groups explained above for the substituents represented by are also the same. X111 and R X112 Preferred is a hydrogen atom.

[0181] L in formula (2) 204 and L 205 Each independently represents a sulfur atom or -X 104 =X 105 -, preferably a sulfur atom. 104 and X 105 The meaning of X is the same as that of X in formula (1) 104 and X 105 The meanings are the same, and the preferred ranges are also the same.

[0182] Ar in formula (2) 201 and Ar 202 Respectively independently represent -(CR Ar201 =CR Ar202 ) n201 -, an arylene group, a heterocyclic group or a group formed by combining two or more of these groups, R Ar201 and R Ar202 R each independently represents a hydrogen atom or a substituent, and n201 represents an integer of 1 to 3. Ar201 , R Ar202 and n201 have the same meaning as R in formula (1). Ar101 , R Ar102 and n101 have the same meanings and preferred ranges are also the same.

[0183] Ar in formula (2) 201 and Ar 202 Preferably, each independently is -(CR Ar201 =CR Ar202 ) n201 -, arylene group or a group formed by combining these.

[0184] As a preferred embodiment, Ar 201 and Ar 202 Each independently represents an arylene group.

[0185] As another preferred embodiment, Ar 201 and Ar 202 Each independently Ar201 =CR Ar202 ) n201 - and arylene groups. Ar201 =CR Ar202 ) n201 The group formed by combining - and an arylene group is preferably - *1 -(CR Ar201 =CR Ar202 ) n201 -Arylene- *2 .and,*2 Preferably, Y of formula (2) 201 or Y 202 The bonding key.

[0186] In formula (2), Ar 201 With X 201 They may be bonded via a single bond or a divalent linking group to form a 5-membered ring or a 6-membered ring.

[0187] Ar 201 With Y 201 They may be bonded via a single bond or a divalent linking group to form a 5-membered ring or a 6-membered ring.

[0188] Ar 202 With X 202 They may be bonded via a single bond or a divalent linking group to form a 5-membered ring or a 6-membered ring.

[0189] Ar 202 With Y 202 The rings may be bonded via a single bond or a divalent linking group to form a 5-membered ring or a 6-membered ring.

[0190] Examples of the divalent linking group include -CR Y21 R Y122 , -O-, -S-, and groups formed by combining two or more of these. Y121 and R Y122 Each independently represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group or a heteroaryl group. These groups may also have a substituent. As a substituent, the groups listed in the substituent T described later, the groups containing anions described later, the groups containing ethylenic unsaturated bonds, etc. can be cited.

[0191] The dye A1 is also preferably a dye (compound) represented by formula (4).

[0192] [Chemical formula 5]

[0193]

[0194] In the formula, Ar 401 represents an aryl or heteroaryl group,

[0195] R 401 ~R 404 each independently represents a hydrogen atom, an alkyl group, an aryl group or a heteroaryl group,

[0196] R 405 and R 406 each independently represents an alkyl group, an aryl group, a heteroaryl group, an aryloxy group, a heteroaryloxy group, an alkoxy group or a cyano group,

[0197] R 407 and R 408each independently represents an alkyl group or an aryl group,

[0198] n401 and n402 each independently represent an integer of 0 to 4,

[0199] q4 means 1 or 2,

[0200] Z 4 It represents a counter anion with a valence of q4.

[0201] Ar 401 The number of carbon atoms of the aryl group represented is preferably 6 to 20, more preferably 6 to 12. Furthermore, the aryl group is preferably a monocyclic aryl group.

[0202] Ar 401 The heteroaryl represented by is preferably a 5-membered ring or a 6-membered ring. The heteroatom constituting the ring of the heteroaryl is preferably an oxygen atom, a nitrogen atom, and a sulfur atom. The number of heteroatoms constituting the ring of the heteroaryl is preferably 1 to 3.

[0203] The above-mentioned aryl group and heteroaryl group may further have a substituent. As the substituent, there may be mentioned the groups listed in the substituent T described later, the group containing anions described later, the group containing ethylenically unsaturated bonds, etc. As the group containing ethylenically unsaturated bonds, there may be mentioned vinyl, (meth)allyl, (meth)acryloyl, etc.

[0204] Ar 401 It is preferably an aryl group, more preferably a monocyclic aryl group, further preferably a monocyclic aryl group having a substituent, and particularly preferably a monocyclic aryl group having a substituent at the ortho position. As the substituent, there can be mentioned the groups listed in the substituent T described later, the group containing anions described later, the group containing ethylenically unsaturated bonds, etc., preferably an alkyl group, a sulfo group, a carboxyl group, a salt of a carboxyl group, a salt of a sulfo group, the group containing anions described later, or the group containing ethylenically unsaturated bonds.

[0205] R 401 ~R 404 Each independently represents a hydrogen atom, an alkyl group, an aryl group or a heteroaryl group, and is preferably an alkyl group or an aryl group.

[0206] R 401 ~R 404 The number of carbon atoms of the alkyl group represented is preferably 1 to 10, more preferably 1 to 6, and further preferably 1 to 4. The alkyl group may be any of a linear, branched, and cyclic group. The alkyl group may further have a substituent. As the substituent, there may be mentioned the groups listed in the substituent T described later, the groups containing anions described later, the groups containing ethylenically unsaturated bonds, and the like.

[0207] R 401 ~R 404The number of carbon atoms of the aryl group represented is preferably 6 to 20, more preferably 6 to 12. In addition, the aryl group is preferably a monocyclic aryl group. The aryl group may further have a substituent. As the substituent, there may be mentioned the groups listed in the substituent T described later, the groups containing anions described later, the groups containing ethylenically unsaturated bonds, etc.

[0208] R 401 ~R 404 The heteroaryl represented is preferably a 5-membered ring or a 6-membered ring. The heteroatoms constituting the ring of the heteroaryl are preferably oxygen atoms, nitrogen atoms and sulfur atoms. The number of heteroatoms constituting the ring of the heteroaryl is preferably 1 to 3. The heteroaryl group may further have a substituent. As the substituent, the groups listed in the substituent T described later, the groups containing anions described later, the groups containing ethylenically unsaturated bonds, etc. may be mentioned.

[0209] R 405 and R 406 Each independently represents an alkyl group, an aryl group, a heteroaryl group, an aryloxy group, a heteroaryloxy group, an alkoxy group or a cyano group.

[0210] n401 and n402 each independently represent an integer of 0 to 4, preferably an integer of 0 to 2, more preferably 0 or 1, and further preferably 0.

[0211] As Z 4 Examples of the q4-valent counter anions represented by include the above-mentioned counter anions.

[0212] The dye A1 is also preferably a dye (compound) represented by formula (5).

[0213] [Chemical formula 6]

[0214]

[0215] In the formula, Ar 501 represents an aryl or heteroaryl group,

[0216] R 501 ~R 504 each independently represents a hydrogen atom, an alkyl group, an aryl group or a heteroaryl group,

[0217] R 505 and R 506 each independently represents an alkyl group, an aryl group, a heteroaryl group, an aryloxy group, a heteroaryloxy group, an alkoxy group or a cyano group,

[0218] n 501 and n 502 Each independently represents an integer from 0 to 4,

[0219] q5 means 1 or 2,

[0220] Z 5It represents a counter anion with a valence of q5.

[0221] Ar in formula (5) 501 , R 501 ~R 506 、n 501 、n 502 , q5 and Z 5 The meaning of is the same as Ar in formula (4) 401 , R 401 ~R 406 、n 401 、n 402 , q4 and Z 4 The meanings are the same, and the preferred ranges are also the same.

[0222] - Pigment polymer A2-

[0223] The specific infrared absorbing dye may be a dye multimer A2 (hereinafter also simply referred to as a dye multimer) containing two or more dye structures derived from the dye A1 in one molecule.

[0224] Examples of pigment polymers include pigment polymers having repeating units represented by formula (A) (hereinafter also referred to as pigment polymers (A)), pigment polymers having repeating units represented by formula (C) (hereinafter also referred to as pigment polymers (C)), and pigment polymers represented by formula (D) (hereinafter also referred to as pigment polymers (D)), preferably pigment polymers (A) or pigment polymers (D).

[0225] (Pigment polymer (A))

[0226] Pigment multimer (A) comprises the repeating unit represented by formula (A). The ratio of the repeating unit represented by formula (A) is preferably more than 10 mass % of all repeating units constituting pigment multimer (A), more preferably more than 20 mass %, further preferably more than 30 mass %, particularly preferably more than 50 mass %. The upper limit can also be set to below 100 mass %, and can also be set to below 95 mass %.

[0227] [Chemical formula 7]

[0228]

[0229] In formula (A), A 1 represents a trivalent linking group,

[0230] L 1 represents a single bond or a divalent linking group,

[0231] DyeI represents a dye structure derived from the above-mentioned dye A1.

[0232] As A of formula (A)1 The trivalent linking group represented includes poly(meth)acrylic acid-based linking groups, polyalkyleneimine-based linking groups, polyester-based linking groups, polyurethane-based linking groups, polyurea-based linking groups, polyamide-based linking groups, polyether-based linking groups, polystyrene-based linking groups, bisphenol-based linking groups, novolac-based linking groups, etc., preferably poly(meth)acrylic acid-based linking groups.

[0233] L in formula (A) 1 represents a single bond or a divalent linking group. Examples of divalent linking groups include alkylene, arylene, heterocyclic, -CH=CH-, -O-, -S-, -CO-, -COO-, -NR-, -CONR-, -OCO-, -SO-, -SO2-, and linking groups formed by connecting two or more of these. R represents a hydrogen atom, an alkyl, an aryl, or a heterocyclic group.

[0234] The number of carbon atoms of the alkylene group is preferably 1 to 30. The upper limit is more preferably 25 or less, and further preferably 20 or less. The lower limit is more preferably 2 or more, and further preferably 3 or more. The alkylene group may be linear, branched, or cyclic. The alkylene group may have a substituent or may be unsubstituted.

[0235] The number of carbon atoms in the arylene group is preferably 6 to 20, more preferably 6 to 12. The arylene group may have a substituent or may be unsubstituted.

[0236] The heterocyclic group is preferably a 5-membered ring or a 6-membered ring. The heteroatom constituting the ring of the heterocyclic group is preferably an oxygen atom, a nitrogen atom and a sulfur atom. The number of heteroatoms constituting the ring of the heterocyclic group is preferably 1 to 3. The heterocyclic group may have a substituent or may be unsubstituted.

[0237] L 1 It is preferably an alkylene group, an arylene group, -NH-, -CO-, -O-, -COO-, -OCO-, -S-, or a linking group formed by combining two or more of these, and more preferably a linking group formed by combining at least one selected from an alkylene group and an arylene group with one or more selected from -O-, -COO-, -OCO-, and -S-. 1 The divalent linking group represented by is also preferably a group containing -S- or -O-.

[0238] In L 1 In the connection between DyeI and A 1 The number of atoms in the chain is preferably 2 or more, more preferably 3 or more. The upper limit can be, for example, 30 or less, or 25 or less.

[0239] The dye structure derived from dye A1 represented by DyeI in formula (A) is preferably a residue obtained by removing one hydrogen atom from the dye (dye A1) represented by the above formula (1).

[0240] Furthermore, it is preferred that X in formula (1) 101 ~X 103 , L 101 ~L 103 ,Ar 101 ,Ar 102 , Y 101 , Y 102 Any part of the formula (A) contains L 1 The connecting part of X is more preferably X of formula (1) 103 Containing L of formula (A) 1 The connection part.

[0241] Pigment polymer (A) can also comprise other repeating units except the repeating unit represented by formula (A).About other repeating units, can enumerate the repeating unit with polymerizable group, the repeating unit with acid group etc.As polymerizable group, can enumerate the group containing ethylenic unsaturated bond etc. such as vinyl, (methyl) allyl, (methyl) acryloyl etc.As acid group, can enumerate carboxyl, sulfo group, phosphoric acid group etc.

[0242] The ratio of the repeating unit with polymerizable group is preferably below 50 mass % of all repeating units constituting the pigment multimer (A). The lower limit is preferably above 1 mass %, more preferably above 3 mass %. The upper limit is preferably below 35 mass %, more preferably below 30 mass %.

[0243] The ratio of the repeating unit with acid group is preferably below 50 mass % of all repeating units constituting the pigment polymer (A). The lower limit is preferably above 1 mass %, more preferably above 3 mass %. The upper limit is preferably below 35 mass %, more preferably below 30 mass %.

[0244] About pigment multimer (A), can be synthesized by the following method: (1) method of synthesizing pigment A1 with polymerizable group by addition polymerization; and (2) method of making polymer with high reactive functional groups such as isocyanate group, anhydride group or epoxy group react with pigment A1 with functional groups (hydroxyl group, primary amino group or secondary amino group, carboxyl group, etc.) that can react with high reactive functional groups, etc. Addition polymerization can be applied to known addition polymerization (free radical polymerization, anionic polymerization, cationic polymerization), wherein, when synthesized by free radical polymerization in particular, reaction conditions can be softened, and pigment skeleton is not decomposed, so it is preferred. Free radical polymerization can be applied to known reaction conditions. From the viewpoint of heat resistance, pigment multimer (A) is preferably a free radical polymer obtained by free radical polymerization using pigment A1 with ethylenically unsaturated bond.

[0245] (Pigment polymer (C))

[0246] Pigment polymer (C) comprises the repeating unit represented by formula (C). The ratio of the repeating unit represented by formula (C) is preferably more than 10 mass % of all repeating units constituting pigment polymer (C), more preferably more than 20 mass %, further preferably more than 30 mass %, particularly preferably more than 50 mass %. The upper limit can also be set to below 100 mass %, and can also be set to below 95 mass %.

[0247] [Chemical formula 8]

[0248]

[0249] In formula (C), L 3 represents a single bond or a divalent linking group,

[0250] DyeIII represents a pigment structure derived from the above-mentioned pigment A1,

[0251] m represents 0 or 1.

[0252] L in formula (C) 3 represents a single bond or a divalent linking group. Examples of divalent linking groups include alkylene, arylene, heterocyclic, -CH=CH-, -O-, -S-, -CO-, -COO-, -NR-, -CONR-, -OCO-, -SO-, -SO2-, and linking groups formed by connecting two or more of these. R each independently represents a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group.

[0253] The number of carbon atoms in the alkyl group and the alkylene group is preferably 1 to 30. The upper limit is more preferably 25 or less, and further preferably 20 or less. The lower limit is more preferably 2 or more, and further preferably 3 or more. The alkyl group and the alkylene group may be linear, branched, or cyclic.

[0254] The aryl group and the arylene group preferably have 6 to 20 carbon atoms, and more preferably 6 to 12 carbon atoms.

[0255] The heterocyclic group is preferably a 5-membered ring or a 6-membered ring. The heteroatom constituting the ring of the heterocyclic group is preferably an oxygen atom, a nitrogen atom, and a sulfur atom. The number of heteroatoms constituting the ring of the heterocyclic group is preferably 1 to 3.

[0256] The alkylene group, arylene group, heterocyclic group, alkyl group and aryl group may be unsubstituted or may have a substituent. Examples of the substituent include the groups exemplified in the substituent T described below, polymerizable groups and acid groups.

[0257] L in formula (C) 3 Preferred are an alkylene group, an arylene group, -NH-, -CO-, -O-, -COO-, -OCO-, -S-, -SO2-, and a linking group formed by combining two or more of these.

[0258] The dye structure derived from dye A1 represented by DyeIII of formula (C) is preferably a residue obtained by removing two hydrogen atoms from the dye (dye A1) represented by the above formula (1).

[0259] Furthermore, it is preferred that X in formula (1) 101 ~X 103 , L 101 ~L 103 ,Ar 101 ,Ar 102 , Y 101 , Y 102 Any part of the formula (A) contains L 1 The connection part.

[0260] In formula (C), m represents 0 or 1, and is preferably 1.

[0261] The dye multimer (C) may contain other repeating units described in the dye multimer (A) in addition to the repeating unit represented by the general formula (C).

[0262] (Pigment polymer (D))

[0263] The pigment multimer (D) is a compound represented by formula (D).

[0264] [Chemical formula 9]

[0265]

[0266] In formula (D), L 4 represents a (n+k)-valent linking group,

[0267] n represents an integer from 2 to 20,

[0268] k represents an integer from 0 to 20,

[0269] DyeIV represents a pigment structure derived from the above-mentioned pigment A1,

[0270] P 4 represents a substituent,

[0271] n DyeIVs can be different from each other.

[0272] When k is greater than 2, multiple P 4 Can be different from each other,

[0273] n+k represents an integer from 2 to 20.

[0274] In formula (D), n is preferably 2-14, more preferably 2-8, particularly preferably 2-7, and even more preferably 2-6.

[0275] k in formula (D) is preferably 0 to 13. The lower limit may be 1 or more, or 2 or more. The upper limit is preferably 10 or less, more preferably 8 or less, further preferably 7 or less, and further preferably 6 or less.

[0276] As L in formula (D) 4 The (n+k)-valent linking group represented by the above-mentioned may be a group consisting of 1 to 100 carbon atoms, 0 to 10 nitrogen atoms, 0 to 50 oxygen atoms, 1 to 200 hydrogen atoms, and 0 to 20 sulfur atoms. As the (n+k)-valent linking group, the following structural unit or a group consisting of two or more of the following structural units combined (which may form a ring structure) is preferred. The * in the following formula represents a bonding bond.

[0277] [Chemical formula 10]

[0278]

[0279] L 4 The (n+k)-valent linking group represented is preferably a linking group derived from a polyfunctional thiol, a linking group derived from a polyfunctional alcohol, or a linking group derived from an acid anhydride, and more preferably a linking group derived from a polyfunctional thiol.

[0280] L 4 The (n+k)-valent connecting group represented by is preferably a group represented by any one of formulae (Za-1) to (Za-5).

[0281] [Chemical formula 11]

[0282]

[0283] In formula (Za-1), La 2Represents a divalent group, Ta 2 Represents a single bond or a divalent linking group, and there are two Ta 2 They can be the same as each other or different.

[0284] In formula (Za-2), La 3 Represents a trivalent group, Ta 3 Represents a single bond or a divalent linking group, and there are three Ta 3 They can be the same as each other or different.

[0285] In formula (Za-3), La 4 represents a tetravalent group, Ta 4 Represents a single bond or a divalent linking group, and there are 4 Ta 4 They can be the same as each other or different.

[0286] In formula (Za-4), La 5 It represents a pentavalent group, Ta 5 Represents a single bond or a divalent linking group, and there are 5 Ta 5 They can be the same as each other or different.

[0287] In formula (Za-5), La 6 Represents a hexavalent group, Ta 6 Represents a single bond or a divalent linking group, and there are 6 Ta 6 They can be the same as each other or different.

[0288] In the above formula, * represents a bonding bond.

[0289] As La 2 、 2 ~Ta 6 The divalent linking group represented by the compound may include an alkylene group, an arylene group, a heterocyclic group, -CH=CH-, -O-, -S-, -CO-, -COO-, -NR-, -CONR-, -OCO-, -SO-, -Sc2-, and a linking group formed by connecting two or more of these. R independently represents a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group.

[0290] The number of carbon atoms in the alkyl group and the alkylene group is preferably 1 to 30. The upper limit is more preferably 25 or less, and further preferably 20 or less. The lower limit is more preferably 2 or more, and further preferably 3 or more. The alkyl group and the alkylene group may be linear, branched, or cyclic.

[0291] The aryl group and the arylene group preferably have 6 to 20 carbon atoms, and more preferably 6 to 12 carbon atoms.

[0292] The heterocyclic group is preferably a 5-membered ring or a 6-membered ring. The heteroatom constituting the ring of the heterocyclic group is preferably an oxygen atom, a nitrogen atom, and a sulfur atom. The number of heteroatoms constituting the ring of the heterocyclic group is preferably 1 to 3.

[0293] The alkylene group, arylene group, heterocyclic group, alkyl group and aryl group may be unsubstituted or may have a substituent. Examples of the substituent include the groups exemplified in the substituent T described below, polymerizable groups and acid groups.

[0294] As La 3 The trivalent group represented by can be a group obtained by removing one hydrogen atom from the above-mentioned divalent linking group. 4 The tetravalent group represented by can be a group obtained by removing two hydrogen atoms from the above-mentioned divalent linking group. 5 The pentavalent group represented by can be a group obtained by removing three hydrogen atoms from the above-mentioned divalent linking group. 6 The hexavalent group represented by can be a group obtained by removing four hydrogen atoms from the above-mentioned divalent linking group. 3 ~La 6 The tri- to hexavalent groups represented by may have the above-mentioned substituents.

[0295] Specific examples of the (n+k)-valent linking group include the linking groups described in paragraphs 0071 to 0072 of JP-A-2008-222950, ​​the linking groups described in paragraph 0176 of JP-A-2013-029760, and the linking groups described in paragraphs 0022 to 0024 of International Publication No. 2016 / 031442.

[0296] The dye structure derived from dye A1 represented by DyeIV of formula (D) is preferably a residue obtained by removing one hydrogen atom from the dye (dye A1) represented by the above formula (1).

[0297] Furthermore, it is preferred that X in formula (1) 101 ~X 103 , L 101 ~L 103 ,Ar 101 ,Ar 102 , Y 101 , Y 102 Any part of the formula (A) contains L 1 The connecting part of X is more preferably X of formula (1) 103 Containing L of formula (A) 1 The connection part.

[0298] As P of formula (D) 4The substituent represented by may include the groups listed in the substituent T described later, an acid group, a polymerizable group, and the like. 4 The substituent represented by may be a monovalent polymer chain having a repeating unit. As the monovalent polymer chain having a repeating unit, a monovalent polymer chain having a repeating unit derived from a vinyl compound is preferred. When k is 2 or more, k P 4 It can be the same or different.

[0299] In P 4 When P is a monovalent polymer chain having a repeating unit and k is 1, 4 Preferably, the monovalent polymer chain has 2 to 20 (preferably 2 to 15, more preferably 2 to 10) repeating units derived from a vinyl compound. 4 When k is a monovalent polymer chain having a repeating unit and k is 2 or more, k P 4 The average value of the number of repeating units derived from the vinyl compound in the is preferably 2 to 20 (preferably 2 to 15, more preferably 2 to 10).

[0300] In P 4 In the case of a monovalent polymer chain having repeating units, the number of repeating units and the average value of the number of repeating units can be determined by nuclear magnetic resonance (NMR).

[0301] In P 4 In the case of a monovalent polymer chain having a repeating unit, as a constituent P 4 The repeating unit may include other repeating units described in the description of the embodiment of the dye multimer (A). Other repeating units preferably have one or more selected from the repeating units having an acid group and the repeating units having a polymerizable group.

[0302] In P 4 When containing repeating units containing an acid group, the ratio of repeating units containing an acid group to P 4 The content of all repeating units is preferably 10 to 80 mol %, more preferably 10 to 65 mol %.

[0303] In P 4 When the repeating unit having a polymerizable group is included, the ratio of the repeating unit having a polymerizable group to P 4 The content of all repeating units is preferably 10 to 80 mol %, more preferably 10 to 65 mol %.

[0304] -Substituent T-

[0305] The substituent T may include the following groups: halogen atoms (e.g., fluorine atoms, chlorine atoms, bromine atoms, iodine atoms), alkyl groups (preferably alkyl groups having 1 to 30 carbon atoms), alkenyl groups (preferably alkenyl groups having 2 to 30 carbon atoms), alkynyl groups (preferably alkynyl groups having 2 to 30 carbon atoms), aryl groups (preferably aryl groups having 6 to 30 carbon atoms), amino groups (preferably amino groups having 0 to 30 carbon atoms), alkoxy groups (preferably alkoxy groups having 1 to 30 carbon atoms), aryloxy groups (preferably aryloxy groups having 6 to 30 carbon atoms), heteroaryloxy groups, acyl groups, acyl (preferably an acyl group having 2 to 30 carbon atoms), alkoxycarbonyl (preferably an alkoxycarbonyl group having 2 to 30 carbon atoms), aryloxycarbonyl (preferably an aryloxycarbonyl group having 7 to 30 carbon atoms), heteroaryloxycarbonyl, acyloxy (preferably an acyloxy group having 2 to 30 carbon atoms), acylamino (preferably an acylamino group having 2 to 30 carbon atoms), alkoxycarbonylamino (preferably an alkoxycarbonylamino group having 2 to 30 carbon atoms), aryloxycarbonylamino (preferably an aryloxy group having 7 to 30 carbon atoms), carbonylamino), sulfamoyl (preferably a sulfamoyl group having 0 to 30 carbon atoms), carbamoyl (preferably a carbamoyl group having 1 to 30 carbon atoms), alkylthio (preferably an alkylthio group having 1 to 30 carbon atoms), arylthio (preferably an arylthio group having 6 to 30 carbon atoms), heteroarylthio (preferably a carbonyl group having 1 to 30 carbon atoms), alkylsulfonyl (preferably a carbonyl group having 1 to 30 carbon atoms), arylsulfonyl (preferably a carbonyl group having 6 to 30 carbon atoms), heteroarylsulfonyl (preferably a carbonyl group having 1 to 30 carbon atoms), 0), alkylsulfinyl group (preferably having 1 to 30 carbon atoms), arylsulfinyl group (preferably having 6 to 30 carbon atoms), heteroarylsulfinyl group (preferably having 1 to 30 carbon atoms), urea group (preferably having 1 to 30 carbon atoms), hydroxyl group, carboxyl group, carboxyl salt, sulfo group, sulfo salt, phosphate group, phosphate salt, carboxylic acid amide group, sulfonic acid amide group, imidic acid group, mercapto group, cyano group, alkylsulfinyl group, arylsulfinyl group, hydrazine group, imino group, heteroaryl group (preferably having 1 to 30 carbon atoms). In the salt of carboxyl group, the salt of sulfonyl group and the salt of phosphate group, examples of the atom or atomic group constituting the salt include alkali metal ion (Li + 、Na + , K + etc.), alkaline earth metal ions (Ca 2+ Mg 2+ The present invention also includes alkyl ions (such as tetraalkyl ammonium ions, trialkyl ammonium ions, etc.), imidazolium ions, pyridinium ions (pyridinium ions, N-methylpyridinium ions and N-ethylpyridinium ions, etc.), phosphonium ions, etc. In the case where these groups are further substitutable groups, they may also have a substituent. As the substituent, the groups described in the substituent T above can be cited.

[0306] -Groups containing anions-

[0307] Examples of the group containing an anion include a group represented by formula (P-1) and a group represented by formula (P-2).

[0308] [Chemical formula 12]

[0309] *-Lp 1 -Xp 1 (P-1)

[0310]

[0311] Lp of formula (P-1) 1 represents a single bond or a divalent linking group. 1 Examples of the divalent linking group represented by include an alkylene group having 1 to 6 carbon atoms, an arylene group having 6 to 12 carbon atoms, -NR Lp1 -, -O-, -S-, -CO-, -SO2- or a group consisting of a combination thereof. At least a portion of the hydrogen atoms of the above-mentioned alkylene group is preferably substituted with a fluorine atom, more preferably a perfluoroalkyl group. As a specific example of such an alkylene group, difluoromethylene, tetrafluoroethylene, hexafluoropropylene, etc. can be cited. At least a portion of the hydrogen atoms of the above-mentioned arylene group is preferably substituted with a fluorine atom. As a specific example of such an arylene group, tetrafluorophenylene, hexafluoro-1-naphthylene, hexafluoro-2-naphthylene, etc. can be cited.

[0312] Lp of formula (P-1) 1 Preferably, a single bond, -NR Lp1 - and -SO2 and an alkylene group containing a fluorine atom, a group composed of a combination of -O- and an arylene group containing a fluorine atom, or a group composed of -NR Lp1 A group consisting of a combination of - and -SO2 and an alkylene group containing a fluorine atom.

[0313] Xp of formula (P-1) 1 Represents -SO3 - 、-COO - ,-PO4H - or an anion containing a boron atom, preferably -SO3 - or -COO - .

[0314] Lp of formula (P-2) 2 represents a single bond or a divalent linking group, preferably a single bond. 2 Examples of the divalent linking group represented by include an alkylene group having 1 to 6 carbon atoms, an arylene group having 6 to 12 carbon atoms, -0-, -S-, or a group consisting of a combination thereof.

[0315] Lp of formula (P-2) 3It represents -SO2- or -CO-, preferably -SO2-.

[0316] G in formula (P-2) represents a carbon atom or a nitrogen atom, and is preferably a nitrogen atom.

[0317] In the formula (P-2), n represents 2 when G is a carbon atom, and represents 1 when G is a nitrogen atom.

[0318] Rp of formula (P-2) 1 represents an alkyl group containing a fluorine atom or an aryl group containing a fluorine atom. When n is 2, two Rp 1 They can be the same or different. 1 The number of carbon atoms in the fluorine-containing alkyl group represented by is preferably 1 to 10, more preferably 1 to 6, and still more preferably 1 to 3. 1 The number of carbon atoms of the fluorine-containing aryl group represented is preferably 6 to 20, more preferably 6 to 14, and even more preferably 6 to 10. The fluorine-containing alkyl group and the fluorine-containing aryl group may further have a substituent. Examples of the substituent include the groups listed in the substituent T above.

[0319] From the viewpoint of the decomposition of the pigment A1 preventing being caused by single electron reduction or nucleophilic reagent, LUMO (Lowest Unoccupied Molecular Orbital: minimum unoccupied molecular orbital) energy level of pigment A1 is preferably high.The LUMO energy level of pigment A1 is preferably more than-6.5eV, more preferably more than-6.0eV, further preferably more than-5.5eV.About the LUMO energy level of pigment A1, for example, can be by using quantum chemical calculation program Gaussian09, under the condition of universal function B3LYP / basis function 6-31g (d) / vacuum, the structure of the cationic part of pigment A1 is implemented structure optimization calculation to obtain.

[0320] -About specific examples-

[0321] As the specific example of specific infrared absorbing pigment, the compound of the structure shown below can be enumerated. The resonance structure of these compounds can also be enumerated as the specific example of specific compound. In the structural formula shown below, Bu represents butyl, and Ph represents phenyl.

[0322] [Chemical formula 13]

[0323]

[0324] [Chemical formula 14]

[0325]

[0326] [Chemical formula 15]

[0327]

[0328] [Chemical formula 16]

[0329]

[0330] [Chemical formula 17]

[0331]

[0332] [Chemical formula 18]

[0333]

[0334] [Chemical formula 19]

[0335]

[0336] [Chemical formula 20]

[0337]

[0338] [Chemical formula 21]

[0339]

[0340] [Chemical formula 22]

[0341]

[0342] The compound represented by formula (4) can be synthesized, for example, by a known method according to the following synthesis scheme. Synthesis conditions such as the type and amount of the solvent, catalyst, and reagent used, and the reaction time and reaction temperature can be adjusted appropriately.

[0343] [Chemical formula 23]

[0344]

[0345] [Chemical formula 24]

[0346]

[0347] [Chemical formula 25]

[0348]

[0349] [Chemical formula 26]

[0350]

[0351] Compound 4A is reacted with a brominating agent such as N-bromosuccinimide (NBS) to obtain compound 4B. Then, bis-pinacol borane is reacted in the presence of a palladium catalyst to obtain 4C in which bromine is replaced by boron.

[0352] Compound 4D synthesized by a known method is subjected to lithiation of the bromine site with alkyl lithium and then reacted with a silicon dichloride compound to obtain compound 4E. Compound 4E is reacted with alkyl lithium and then with 1,2-dibromo-1,1,2,2-tetrachloroethane to obtain compound 4F.

[0353] Compound 4C is reacted with compound 4F in the presence of a palladium catalyst (Suzuki-Miyaura reaction conditions) to obtain compound 4G. Compound 4G is reacted under acidic conditions to deprotect the acetal site, thereby synthesizing compound 4H.

[0354] Compound 4H is reacted with a Grignard reagent to obtain compound 4I. Compound 4I is then reacted under acidic conditions to obtain compound 4J.

[0355] By reacting a salt compound having a target anion with compound 4J, a compound represented by formula (4) in which a chloride anion is exchanged for a target anion can be obtained.

[0356] The compound represented by formula (5) can be synthesized in the same manner as in the synthesis of the compound represented by formula (4), except that thionyl chloride is used instead of the silicon dichloride compound in the synthesis step of compound 4E.

[0357] The maximum absorption wavelength of the specific infrared absorbing pigment is preferably within the wavelength range of 700 to 1800 nm, more preferably within the wavelength range of 1000 to 1800 nm, further preferably within the wavelength range of 1030 to 1750 nm, further preferably within the wavelength range of 1050 to 1700 nm, and further preferably within the wavelength range of 1070 to 1650 nm.

[0358] Absorbance A at the maximum absorption wavelength of a specific infrared absorbing pigment max Absorbance A at the wavelength of maximum absorption wavelength + 200nm max+200 The ratio is A max+200 / A max It is preferably 4.5 or more, more preferably 10 or more, and further preferably 30 or more. The upper limit is, for example, preferably 90 or less.

[0359] The content of specific infrared absorption pigment is preferably 0.1 to 20 mass % relative to the gross mass of inkjet recording ink. The lower limit is preferably 0.2 mass % or more, more preferably 0.3 mass % or more. The upper limit is preferably 10 mass % or less, more preferably 5 mass % or less. If the content of specific infrared absorption pigment is 0.1 mass % or more, an infrared absorption image with better readability can be obtained. If the content of specific infrared absorption pigment is 20 mass % or less, it is advantageous from the viewpoint of discharge stability. And, it is also possible to further improve storage stability.

[0360] Solvents

[0361] The inkjet recording ink of the present invention may contain a solvent.

[0362] The solvent is not particularly limited, and any solvent known in the field of inkjet recording inks can be used.

[0363] As a preferred embodiment of the inkjet recording ink of the present invention, an embodiment as an aqueous ink can be mentioned. In such an inkjet recording ink, the inkjet recording ink preferably contains water.

[0364] The content of water is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 70% by mass or more relative to the total mass of the inkjet recording ink. The upper limit of the water content is not particularly limited, as long as it is determined according to the contents of other components, but is preferably 99% by mass or less, more preferably 98% by mass or less, and further preferably 95% by mass or less. This inkjet recording ink is preferably used as an aqueous ink.

[0365] From the viewpoint of improving the ejection properties of the ink, it is also preferred that the solvent contain water and an organic solvent having a boiling point at 101.325 kPa (hereinafter also simply referred to as "boiling point") of 100°C or higher. 101.325 kPa has the same meaning as 1 atmospheric pressure.

[0366] Examples of the organic solvent having a boiling point of 100° C. or higher include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, glycerin, 2-pyrrolidone, butanediol, and hexanediol.

[0367] When the inkjet recording ink contains water and an organic solvent having a boiling point of 100° C. or more, the content of the organic solvent having a boiling point of 100° C. or more is preferably 1 to 40% by mass, more preferably 2 to 30% by mass, relative to the total mass of the inkjet recording ink. In addition, the content of water is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 70% by mass or more relative to the total mass of the inkjet recording ink. The upper limit of the water content is not particularly limited, as long as it is determined according to the content of other components, but is preferably 99% by mass or less, more preferably 98% by mass or less, and further preferably 95% by mass or less.

[0368] In the case where the inkjet recording ink of the present invention is a photocurable ink containing a free radical polymerizable monomer and a photo radical polymerization initiator described later, the inkjet recording ink may further contain an organic solvent. Examples of the organic solvent include ketones such as acetone, methyl ethyl ketone, and diethyl ketone; alcohols such as methanol, ethanol, 2-propanol, 1-propanol, 1-butanol, and tert-butanol; chlorine-based solvents such as chloroform and dichloromethane; aromatic solvents such as benzene and toluene; ester solvents such as ethyl acetate, butyl acetate, isopropyl acetate, ethyl lactate, butyl lactate, and isopropyl lactate; ether solvents such as diethyl ether, tetrahydrofuran, and dioxane; glycol ether solvents such as ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, and propylene glycol monomethyl ether; and glycol ether acetate solvents such as propylene glycol monomethyl ether acetate.

[0369] In the case where the inkjet recording ink of the present invention is a photocurable ink comprising a free radical polymerizable monomer and a photo radical polymerization initiator described later, the content of the organic solvent is preferably 1% by mass or less, more preferably 0.5% by mass or less, and further preferably 0.1% by mass or less relative to the total mass of the inkjet recording ink. The inkjet recording ink may be a composition that does not contain an organic solvent (i.e., the content of the organic solvent is 0% by mass relative to the total mass of the inkjet recording ink).

[0370] Furthermore, when the inkjet recording ink of the present invention is a photocurable ink containing a radical polymerizable monomer and a photoradical polymerization initiator described below, the content of water is preferably 3% by mass or less, more preferably 2% by mass or less, and further preferably 1% by mass or less relative to the total mass of the inkjet recording ink. The inkjet recording ink is preferably a non-aqueous ink that does not substantially contain water.

[0371] Resin particles

[0372] The inkjet recording ink of the present invention may contain resin particles. By containing resin particles, an infrared absorption image with excellent wear resistance can be easily obtained. When the inkjet recording ink of the present invention is used as an aqueous ink, the inkjet recording ink of the present invention preferably contains resin particles.

[0373] The resin particles are not particularly limited as long as they are particles containing resin, but are preferably particles composed of resin. The shape of the resin particles is not particularly limited, and may be irregularly shaped, polyhedral or hollow particles, and preferably spherical particles from the viewpoint of ejectability in the inkjet method.

[0374] About resin particles, for example, particles of resins having anionic groups such as thermoplastic, thermosetting or modified acrylic, epoxy, polyurethane, polyether, polyamide, unsaturated polyester, phenol, silicone or fluorine resins, polyethylene resins such as vinyl chloride, vinyl acetate, polyvinyl alcohol or polyvinyl butyral, polyester resins such as alkyd resins and phthalic acid resins, melamine resins, melamine formaldehyde resins, aminoalkyd polycondensation resins, urea resins, urea resins, amino materials, or copolymers or mixtures thereof can be cited. Among these resin particles, anionic acrylic resins are obtained, for example, by polymerizing acrylic monomers having anionic groups (acrylic monomers containing anionic groups) and other monomers that can be copolymerized with acrylic monomers containing anionic groups as required in a solvent. Examples of the anionic group-containing acrylic monomer include acrylic monomers having one or more selected from a carboxyl group, a sulfonic acid group, and a phosphonic acid group. Among them, acrylic monomers having a carboxyl group (for example, acrylic acid, methacrylic acid, crotonic acid, ethacrylic acid, propyl acrylic acid, isopropyl acrylic acid, itaconic acid, fumaric acid, etc.) are preferred, and acrylic acid or methacrylic acid is particularly preferred.

[0375] From the viewpoint of abrasion resistance and dot shape, particles comprising acrylic resin, vinyl acetate resin, styrene-butadiene resin, vinyl chloride resin, urethane resin, acrylic-styrene resin, butadiene resin, styrene resin, cross-linked acrylic resin, cross-linked styrene resin, polyethylene resin, etc. are preferred, and particles comprising at least one type of resin selected from acrylic resin particles, urethane resin particles, polyethylene resin particles, and styrene-acrylic resin particles are further preferred, and particles comprising acrylic resin particles are more preferred.

[0376] As the resin particles, from the viewpoint of the stability of the ejected ink (particularly the dispersion stability), particles of a self-dispersible resin (self-dispersible resin particles) are preferred. The self-dispersible resin refers to a water-insoluble polymer that can be dispersed in an aqueous medium by a functional group (particularly an acidic group or its salt) possessed by the polymer itself when it is dispersed by a phase inversion emulsification method in the absence of a surfactant.

[0377] Among them, the dispersion state is a state including an emulsified state (emulsion) in which a water-insoluble polymer is dispersed in a liquid state in an aqueous medium and a dispersion state (suspension) in which a water-insoluble polymer is dispersed in a solid state in an aqueous medium. In addition, the aqueous medium refers to a medium containing water. The aqueous medium may contain a hydrophilic organic solvent as required. The aqueous medium preferably contains water and a hydrophilic organic solvent of 0.2 mass % or less relative to water, and more preferably contains only water.

[0378] As the self-dispersible resin, from the viewpoint of aggregation speed and fixability when contained in ink, self-dispersible resin particles capable of being in a dispersed state in which a water-insoluble polymer is dispersed in a solid state are preferred.

[0379] As a method for obtaining an emulsified state or a dispersed state of a self-dispersible resin, that is, a method for preparing an aqueous dispersion of self-dispersible resin particles, a phase inversion emulsification method can be cited. As a phase inversion emulsification method, for example, the following method can be cited: after dissolving or dispersing a self-dispersible resin in a solvent (for example, a water-soluble organic solvent, etc.), the self-dispersible resin is directly put into water without adding a surfactant, and the salt-forming group (for example, an acidic group) of the self-dispersible resin is neutralized. After stirring and mixing, the solvent is removed to obtain an aqueous dispersion in an emulsified state or a dispersed state.

[0380] A stable emulsified state or dispersed state in a self-dispersible resin means that after a solution obtained by dissolving 30 g of a water-insoluble polymer in 70 g of an organic solvent (e.g., methyl ethyl ketone), a neutralizer capable of 100% neutralizing the salt-forming group of the water-insoluble polymer (sodium hydroxide when the salt-forming group is anionic, and acetic acid when the salt-forming group is cationic) and 200 g of water are mixed and stirred (device: a stirring device with a stirring blade, a rotation speed of 200 rpm, 30 minutes, 25° C.), even after the organic solvent is removed from the mixed solution, the emulsified state or dispersed state is a state that exists stably at 25° C. for at least 1 week (i.e., a state in which precipitation cannot be visually confirmed).

[0381] In addition, the stability of the emulsified state or the dispersed state in the self-dispersible resin can also be confirmed by an accelerated test of the sedimentation caused by centrifugation. Regarding the stability of the accelerated test based on the sedimentation caused by centrifugation, for example, the aqueous dispersion of the resin particles obtained by the above method can be adjusted to a solid content concentration of 25% by mass, centrifuged at 12000rpm for 1 hour, and the solid content concentration of the supernatant after centrifugation is measured for evaluation. If the ratio of the solid content concentration after centrifugation to the solid content concentration before centrifugation is large (if it is a numerical value close to 1), it means that the sedimentation of the resin particles caused by centrifugation will not occur, that is, the aqueous dispersion of the resin particles is more stable. The ratio of the solid content concentration before and after centrifugation is preferably 0.8 or more, more preferably 0.9 or more, and particularly preferably 0.95 or more.

[0382] The content of the water-soluble component showing water solubility when the self-dispersible resin becomes a dispersed state is preferably 10% by mass or less, more preferably 8% by mass or less, and further preferably 6% by mass or less. By setting the water-soluble component to 10% by mass or less, the expansion of the resin particles and the fusion between the resin particles are effectively suppressed, and a more stable dispersed state can be maintained. In addition, the viscosity of the inkjet recording ink can be suppressed to rise, for example, when the inkjet recording ink is applied to the inkjet method, the discharge stability becomes better. Here, the water-soluble component refers to a compound contained in the self-dispersible resin and a compound dissolved in water when the self-dispersible resin is in a dispersed state. The water-soluble component is a water-soluble compound that is a byproduct or mixed in when the self-dispersible resin is manufactured.

[0383] The main chain skeleton of the water-insoluble polymer is not particularly limited, and for example, vinyl polymers and condensation polymers (epoxy resins, polyesters, polyurethanes, polyamides, celluloses, polyethers, polyureas, polyimides, polycarbonates, etc.) can be used. Among them, vinyl polymers are particularly preferred.

[0384] As the preferred example of vinyl polymer and the monomer constituting the vinyl polymer, the monomers recorded in writing in Japanese Unexamined Patent Publication No. 2001-181549 and Japanese Unexamined Patent Publication No. 2002-088294 can be enumerated. And, it is also possible to use the vinyl polymer of the dissociative group introduced at the end of the polymer chain by the free radical polymerization of the vinyl monomers using the chain transfer agent or polymerization initiator, iniferter with dissociative group (or the substituent group that can be derived into the dissociative group) or the ionic polymerization of the compound with dissociative group (or the substituent group that can be derived into the dissociative group) in any one of the initiator or terminator. And, as the preferred example of the monomer constituting the condensation system polymer and the monomer constituting the condensation system polymer, the monomers recorded in writing in Japanese Unexamined Patent Publication No. 2001-247787 can be enumerated.

[0385] From the viewpoint of dispersion stability, the resin particles preferably contain a water-insoluble polymer containing a hydrophilic structural unit and a structural unit derived from an aromatic group-containing monomer or a cycloaliphatic group-containing monomer.

[0386] The "hydrophilic structural unit" is not particularly limited as long as it is a structural unit derived from a monomer containing a hydrophilic group, and may be a structural unit derived from one monomer containing a hydrophilic group, or may be a structural unit derived from two or more monomers containing hydrophilic groups. The hydrophilic group is not particularly limited, and may be a dissociative group or a nonionic hydrophilic group.

[0387] From the viewpoint of the stability of the emulsified state or the dispersed state formed, the hydrophilic group is preferably a dissociative group, and more preferably an anionic dissociative group. That is, as the resin particles, resin particles having anionic dissociative groups are preferred. As the dissociative group, carboxyl, phosphoric acid, sulfonic acid, etc. can be cited, and from the viewpoint of fixability, carboxyl is preferred.

[0388] From the viewpoint of dispersion stability and cohesion, the monomer containing a hydrophilic group is preferably a monomer containing a dissociative group, preferably a monomer containing a dissociative group having a dissociative group and an ethylenically unsaturated bond. Examples of monomers containing a dissociative group include unsaturated carboxylic acid monomers, unsaturated sulfonic acid monomers, and unsaturated phosphoric acid monomers.

[0389] Specific examples of the unsaturated carboxylic acid monomer include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, and 2-methacryloyloxymethylsuccinic acid.

[0390] Specific examples of the unsaturated sulfonic acid monomer include styrenesulfonic acid, 2-acrylamide-2-methylpropanesulfonic acid, 3-sulfonyl methacrylate, and bis-(3-sulfonylpropyl)-itaconate.

[0391] Specific examples of the unsaturated phosphoric acid monomer include vinylphosphonic acid, vinyl phosphate, bis(methacryloyloxyethyl)phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, and dibutyl-2-acryloyloxyethyl phosphate.

[0392] Among the dissociative group-containing monomers, unsaturated carboxylic acid monomers are preferred from the viewpoint of dispersion stability and discharge stability, and acrylic acid and methacrylic acid are more preferred.

[0393] From the viewpoint of dispersion stability and the aggregation rate when in contact with the treatment liquid, the resin particles preferably contain a polymer having a carboxyl group, and more preferably contain a polymer having a carboxyl group and an acid value of 25 mgKOH / g to 100 mgKOH / g. In addition, from the viewpoint of self-dispersibility and the aggregation rate when in contact with the treatment liquid, the acid value is more preferably 25 mgKOH / g to 80 mgKOH / g, and particularly preferably 30 mgKOH / g to 65 mgKOH. In particular, when the acid value is 25 mgKOH / g or more, the dispersion stability becomes good, and when the acid value is 100 mgKOH / g or less, the cohesion is improved. The acid value can be measured by the method described in the JIS standard (JISK0070: 1992).

[0394] The monomer containing an aromatic group is not particularly limited as long as it is a compound containing an aromatic group and a polymerizable group. The aromatic group can be a group derived from an aromatic hydrocarbon, or a group derived from an aromatic heterocycle. From the viewpoint of particle shape stability in an aqueous medium, it is preferably an aromatic group derived from an aromatic hydrocarbon. In addition, the polymerizable group can be a condensation-polymerizable group, or it can be an addition-polymerizable group. From the viewpoint of particle shape stability in an aqueous medium, it is preferably an addition-polymerizable group, more preferably a group containing an ethylenically unsaturated bond.

[0395] The monomer containing an aromatic group is preferably a monomer having an aromatic group and an ethylenically unsaturated bond derived from an aromatic hydrocarbon. One monomer containing an aromatic group can be used alone, or two or more monomers can be used in combination. As the monomer containing an aromatic group, for example, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, styrene monomers, etc. can be cited. Among them, from the viewpoint of the balance of hydrophilicity and hydrophobicity of the polymer chain and the fixability of the ink, it is preferably a (meth)acrylate monomer containing an aromatic group, more preferably at least one selected from phenoxyethyl (meth)acrylate, benzyl (meth)acrylate and phenyl (meth)acrylate, and further preferably phenoxyethyl (meth)acrylate and benzyl (meth)acrylate.

[0396] The monomer containing a cycloaliphatic group is preferably a monomer having a cycloaliphatic group derived from a cycloaliphatic hydrocarbon and an ethylenically unsaturated bond, and more preferably a (meth)acrylate monomer containing a cycloaliphatic group (hereinafter, sometimes referred to as alicyclic (meth)acrylate). Alicyclic (meth)acrylate is a compound having a structure containing a constituent part derived from (meth)acrylic acid and a constituent part derived from an alcohol, and having at least one unsubstituted or substituted alicyclic hydrocarbon group (cycloaliphatic group) in the constituent part derived from the alcohol. In addition, the alicyclic hydrocarbon group may be the constituent part derived from the alcohol itself, or may be bonded to the constituent part derived from the alcohol via a linking group.

[0397] The alicyclic hydrocarbon group is not particularly limited as long as it is a hydrocarbon group containing a cyclic non-aromatic hydrocarbon group, and examples thereof include monocyclic hydrocarbon groups, bicyclic hydrocarbon groups, and tricyclic or higher polycyclic hydrocarbon groups. Examples of the alicyclic hydrocarbon group include cycloalkyl groups such as cyclopentyl and cyclohexyl, or cycloalkenyl groups, bicyclohexyl groups, norbornyl groups, isobornyl groups, dicyclopentyl groups, dicyclopentenyl groups, adamantyl groups, decahydronaphthyl groups, perhydrofluorenyl groups, tricyclo[5.2.1.0 2，6 ]decyl and bicyclo[4.3.0]nonane.

[0398] The alicyclic hydrocarbon group may further have a substituent. Examples of the substituent include an alkyl group, an alkenyl group, an aryl group, an aralkyl group, an alkoxy group, a hydroxyl group, a primary amino group, a secondary amino group, a tertiary amino group, an alkylcarbonyl group or an arylcarbonyl group, and a cyano group. Furthermore, the alicyclic hydrocarbon group may also form a condensed ring. As the alicyclic hydrocarbon group, the number of carbon atoms in the alicyclic hydrocarbon group portion is preferably 5 to 20 from the viewpoint of viscosity or solubility.

[0399] As specific examples of the alicyclic (meth)acrylate, the compounds shown below can be mentioned.

[0400] Examples of the monocyclic (meth)acrylate include cycloalkyl (meth)acrylates having 3 to 10 carbon atoms in the cycloalkyl group, such as cyclopropyl (meth)acrylate, cyclobutyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, cyclooctyl (meth)acrylate, cyclononyl (meth)acrylate, and cyclodecyl (meth)acrylate.

[0401] Examples of the bicyclic (meth)acrylate include isobornyl (meth)acrylate and norbornyl (meth)acrylate.

[0402] Examples of the tricyclic (meth)acrylate include adamantyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and dicyclopentenyloxyethyl (meth)acrylate.

[0403] These can be used individually or in mixture of 2 or more types, respectively.

[0404] Among them, from the viewpoints of dispersion stability, fixability and anti-blocking property of the resin particles, it is preferred to use at least one bicyclic (meth)acrylate or tricyclic or higher polycyclic (meth)acrylate, and it is more preferred to use at least one selected from isobornyl (meth)acrylate, adamantyl (meth)acrylate and dicyclopentanyl (meth)acrylate.

[0405] As the resin for forming the resin particles, an acrylic resin containing a structural unit derived from a (meth)acrylate monomer is preferred, and an acrylic resin containing a structural unit derived from a (meth)acrylate monomer containing an aromatic group or an alicyclic (meth)acrylate is preferred, and more preferably, a structural unit derived from a (meth)acrylate monomer containing an aromatic group or an alicyclic (meth)acrylate is further preferred and the content thereof is 10% to 95% by mass. By making the content of the (meth)acrylate monomer containing an aromatic group or an alicyclic (meth)acrylate 10% to 95% by mass, the stability of the emulsified state or the dispersed state can be improved, thereby suppressing the increase in the viscosity of the ink.

[0406] From the viewpoints of the stability of the dispersed state, the stabilization of the particle shape in an aqueous medium due to the hydrophobic interaction between aromatic rings or alicyclic rings, and the reduction in the amount of water-soluble components due to appropriate hydrophobization of the particles, the content of the aromatic group-containing (meth)acrylate monomer or alicyclic (meth)acrylate is more preferably 15% by mass to 90% by mass, more preferably 15% by mass to 80% by mass, and particularly preferably 25% by mass to 70% by mass.

[0407] The resin for forming the resin particles can be composed of, for example, a structural unit derived from a monomer containing an aromatic group or a monomer containing a cyclic aliphatic group and a structural unit derived from a monomer containing a dissociative group, and may contain other structural units as required.

[0408] As monomers forming other structural units, there are no particular restrictions as long as they are monomers that can copolymerize monomers containing aromatic groups and monomers containing dissociative groups. Among them, from the viewpoint of the flexibility of the polymer skeleton and the ease of controlling the glass transition temperature (Tg), monomers containing alkyl groups are preferred. As monomers containing alkyl groups, for example, methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, hexyl (meth)acrylate, ethylhexyl (meth)acrylate and other (meth)acrylate alkyl esters; hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, hydroxypentyl (meth)acrylate, hydroxyhexyl (meth)acrylate and other ethylenically unsaturated monomers having hydroxyl groups; (meth) Dialkylaminoalkyl (meth)acrylates such as dimethylaminoethyl acrylate; N-hydroxyalkyl (meth)acrylamide such as N-hydroxymethyl (meth)acrylamide, N-hydroxyethyl (meth)acrylamide, and N-hydroxybutyl (meth)acrylamide; (meth)acrylamide such as N-methoxymethyl (meth)acrylamide, N-ethoxymethyl (meth)acrylamide, N-(n-, iso)butoxymethyl (meth)acrylamide, N-methoxyethyl (meth)acrylamide, N-ethoxyethyl (meth)acrylamide, and N-(n-, iso)butoxyethyl (meth)acrylamide; and the like.

[0409] From the viewpoint of controlling the hydrophilicity / hydrophobicity of the polymer, the water-insoluble polymer constituting the resin particles preferably contains, in terms of copolymerization ratio, 15 to 80% by mass of a structural unit derived from a (meth)acrylate monomer containing an aromatic group (preferably a structural unit derived from phenoxyethyl (meth)acrylate and / or a structural unit derived from benzyl (meth)acrylate) or a cyclic aliphatic group-containing monomer (preferably an alicyclic (meth)acrylate), based on the total mass of the resin particles.

[0410] Furthermore, from the viewpoint of controlling the hydrophilicity / hydrophobicity of the polymer, the water-insoluble polymer preferably contains, in a copolymerization ratio, 15% to 80% by mass of a structural unit derived from a (meth)acrylate monomer containing an aromatic group or an alicyclic (meth)acrylate monomer, a structural unit derived from a monomer containing a carboxyl group, and a structural unit derived from a monomer containing an alkyl group (preferably a structural unit derived from an alkyl ester of (meth)acrylic acid), and more preferably contains, in a copolymerization ratio, 15% to 80% by mass of a structural unit derived from phenoxyethyl (meth)acrylate and / or a structural unit derived from benzyl (meth)acrylate, a structural unit derived from a monomer containing a carboxyl group, and a structural unit derived from a monomer containing an alkyl group (preferably a structural unit derived from an alkyl ester of (meth)acrylic acid having 1 to 4 carbon atoms).

[0411] The water-insoluble polymer preferably has an acid value of 25 to 100 mgKOH / g and a weight average molecular weight of 3,000 to 200,000, and more preferably has an acid value of 25 to 95 mgKOH / g and a weight average molecular weight of 5,000 to 150,000.

[0412] Specific examples of the water-insoluble polymer constituting the resin particles include exemplified compounds B-01 to B-23 described in paragraph 0046 of International Publication No. 2019 / 163916.

[0413] From the viewpoint of the ejection property of the ink, the volume average particle size of the resin particles is preferably less than 1 μm, more preferably less than 125 nm, and further preferably less than 100 nm. Furthermore, from the viewpoint of the stability of the ink, the volume average particle size of the resin particles is preferably greater than 5 nm, and more preferably greater than 10 nm. The volume average particle size and particle size distribution of the resin particles can be measured using a NANOTRAC particle size distribution measuring device and by a dynamic light scattering method. As a NANOTRAC particle size distribution measuring device, for example, UPA-EX150 of Nikkiso Co., Ltd. can be used. Furthermore, there is no particular limitation on the particle size distribution of the resin particles, and the resin particles can be any one of resin particles having a wide particle size distribution or resin particles having a monodispersed particle size distribution. Furthermore, two or more resin particles can also be used in combination.

[0414] The weight average molecular weight of the resin in the resin particles is preferably 5000 or more, and more preferably 10000 or more. Furthermore, the weight average molecular weight of the resin in the resin particles is preferably 300000 or less, and more preferably 100000 or less.

[0415] In this specification, the number average molecular weight and weight average molecular weight of the resin are values ​​measured by gel permeation chromatography (GPC). Specifically, for GPC, HLC-8220GPC (manufactured by Tosoh Corporation) was used as a measuring device, 3 TSKgels and Super Multipore HZ-H (4.6 mmID×15 cm, Tosoh Corporation) were used as columns, and THF (tetrahydrofuran) was used as an eluent. In addition, as measurement conditions, the sample concentration was set to 0.45% by mass, the flow rate was set to 0.35 ml / min, the sample injection volume was set to 10 μl, and the measurement temperature was set to 40° C., and a differential refractometer (RI) detector was used. The calibration curve was prepared using eight samples of "TSK standard, polystyrene" of Tosoh Corporation: "F-40", "F-20", "F-4", "F-1", "A-5000", "A-2500", "A-1000" and "n-propylbenzene".

[0416] The glass transition temperature (Tg) of the resin in the resin particles is preferably 30°C to 230°C, more preferably 70°C to 230°C, from the viewpoint of abrasion resistance and ink stability.

[0417] In addition, Tg is a value measured under normal measurement conditions using a differential scanning calorimeter (DSC) EXSTAR6220 (manufactured by SII NanoTechnology Inc.). However, when it is difficult to measure due to decomposition of the resin, etc., the calculated Tg calculated by the following calculation formula is applied. The calculated Tg is calculated by the following formula (1).

[0418] 1 / Tg=∑(Xi / Tgi)…(1)

[0419] Here, the polymer to be calculated is a copolymer of n monomer components with i=1 to n. Xi is the mass fraction of the i-th monomer (∑Xi=1), and Tgi is the glass transition temperature (absolute temperature) of the homopolymer of the i-th monomer. However, ∑ is the sum of i=1 to n. In addition, the value of the homopolymer glass transition temperature (Tgi) of each monomer is the value of Polymer Handbook (Polymer Handbook) (3rd edition) (J. Brandrup, EH Immergut (Wiley-Interscience, 1989)).

[0420] The content of the resin particles is not particularly limited, but is preferably 1 to 20% by mass, more preferably 2 to 12% by mass, and preferably 3 to 10% by mass relative to the total mass of the inkjet recording ink. Furthermore, the resin particles are preferably contained in an amount of 60 to 96 parts by mass relative to 100 parts by mass of the total of the specific infrared absorbing pigment and the resin particles.

[0421] Surfactants

[0422] The inkjet recording ink of the present invention can contain a surfactant.

[0423] As the surfactant, a compound having a structure having both a hydrophilic part and a hydrophobic part in the molecule can be used, and any of anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants and betaine-based surfactants can be used.

[0424] As the surfactant, from the viewpoint of suppressing the ejection interference of the ink, a nonionic surfactant is preferred, and an acetylene glycol derivative (acetylene glycol-based surfactant) is more preferred. As the acetylene glycol-based surfactant, for example, 2,4,7,9-tetramethyl-5-decyne-4,7-diol and 2,4,7,9-tetramethyl-5-decyne-4,7-diol alkylene oxide adducts can be cited, and at least one selected from these is preferred. As commercially available products of the acetylene glycol-based surfactant, Surfynol series such as Surfynol 104PG manufactured by Nissin Chemical Co., Ltd. and E series such as OLFINE E1010 manufactured by Nissin Chemical Co., Ltd. can be cited.

[0425] As a surfactant other than the acetylene glycol surfactant, a fluorine-based surfactant is preferred. As a fluorine-based surfactant, an anionic surfactant, a nonionic surfactant and a betaine-based surfactant can be cited, wherein an anionic surfactant is more preferred. As an example of an anionic surfactant, Capstone FS-63, Capstone FS-61 (manufactured by Dupont), Ftergent 100, Ftergent 110, Ftergent 150 (manufactured by Neos), CHEMGU ARD S-760P (manufactured by Chemguard Inc.), etc. can be cited.

[0426] The content of the surfactant is not particularly limited, but is preferably 0.1% by mass or more, more preferably 0.1 to 10% by mass, and even more preferably 0.2 to 3% by mass, relative to the total mass of the inkjet recording ink.

[0427] Water-soluble polymer compounds

[0428] The inkjet recording ink of the present invention can include a water-soluble polymer compound. As a water-soluble polymer compound, it is not particularly limited, as a natural hydrophilic polymer compound or a hydrophilic polymer compound of a synthetic system described in paragraphs 0021 to 0022 of Japanese Patent Publication No. 2010-188661, it is possible to use vinyl polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl methyl ether, polyacrylamide, polyacrylic acid or its alkali metal salt, acrylic resins such as water-soluble styrene acrylic resin, water-soluble styrene maleic acid resin, water-soluble vinyl naphthalene acrylic resin, water-soluble vinyl naphthalene maleic acid resin, polyvinyl pyrrolidone, polyvinyl alcohol, alkali metal salts of β-naphthalenesulfonic acid formalin condensation products, polymer compounds having salts of cationic functional groups such as quaternary ammonium or amino groups on side chains, etc. Among them, it is preferably known water-soluble polymer compounds such as polyvinyl alcohol, polyacrylamide, polyvinyl pyrrolidone, polyethylene glycol, hydroxypropyl methylcellulose, etc.

[0429] The weight average molecular weight of the water-soluble polymer compound is not particularly limited, and can be, for example, 5,000 to 100,000, preferably 10,000 to 80,000, and more preferably 10,000 to 50,000.

[0430] The content of the water-soluble polymer compound is not particularly limited, but is preferably 0.1 to 10% by mass, more preferably 0.1 to 4% by mass, further preferably 0.1 to 2% by mass, and particularly preferably 0.1 to 1% by mass relative to the total mass of the ink for inkjet recording. If the content of the water-soluble polymer compound is 0.1% by mass or more, the diffusion of ink droplets or the penetration of ink into a permeable substrate can be suppressed, and if the content of the water-soluble polymer compound is 10% by mass or less, the thickening of the ink can be further suppressed. In addition, if the content of the water-soluble polymer compound is 2% by mass or less, the ejection property can be well maintained.

[0431] Dispersants

[0432] The inkjet recording ink of the present invention may contain a dispersant for dispersing the specific infrared absorbing pigment. Regarding the dispersant, reference may be made to known documents such as paragraphs 0152 to 0158 of JP-A-2011-225848 and paragraphs 0132 to 0149 of JP-A-2009-209352. Specifically, examples of the dispersant include Lubrizol's SOLSPERSE series (e.g., SOL SPERSE 16000, 21000, 32000, 41000, 41090, 43000, 44000, 46000, 54000, etc.), BYK Co., Ltd.'s DISPERBYK series (e.g., DISPERBYK 102, 110, 111, 118, 170, 190, 194N, 2015, 2090, 2096, etc.), Evonik Industries AG's TEGO Dispers series (e.g., TEGO Dispers 610, 610S, 630, 651, 655, 750W, 755W, etc.), Kusumoto Chemicals, Ltd.'s Disparlon series (e.g., DA-375, DA-1200, etc.), KYOEI CHEMICAL INDUSTRY CO., LTD.'s Floren series (e.g., WK-13E, G-700, G-900, GW-1500, GW-1640, WK-13E, etc.), and Kao Corporation's Demol series (Demol SN-B, etc.).

[0433] The content of the dispersant is not particularly limited, but is preferably 0.1 to 20% by mass, more preferably 0.3 to 10% by mass, and even more preferably 0.3 to 5% by mass, relative to the total mass of the inkjet recording ink.

[0434] Furthermore, the content of the dispersant is preferably 15 to 100 parts by mass, more preferably 20 to 60 parts by mass, based on 100 parts by mass of the specific infrared absorbing pigment.

[0435] 《Free Radical Polymerizable Monomers》

[0436] The inkjet recording ink of the present invention may contain a radical polymerizable monomer. By containing a radical polymerizable monomer, the ink can be made curable. When the inkjet recording ink of the present invention is used as a photocurable ink, the inkjet recording ink of the present invention preferably contains a radical polymerizable monomer and a photo radical polymerization initiator described below.

[0437] The radical polymerizable monomer is a compound that undergoes a polymerization reaction by the action of radicals to obtain a high molecular weight. The radical polymerizable monomer may be either a monofunctional radical polymerizable monomer or a polyfunctional radical polymerizable monomer, or any one of them may be selectively used or both may be used in combination.

[0438] Examples of monofunctional radical polymerizable monomers (hereinafter also referred to as “monofunctional monomers”) include:

[0439] N-vinyl compounds such as N-vinyl-ε-caprolactam and N-vinylpyrrolidone;

[0440] Monofunctional acrylate compounds such as 2-phenoxyethyl acrylate (PEA), benzyl acrylate, cyclic trimethylolpropane formal acrylate (CTFA), isobornyl acrylate (IBOA), tetrahydrofurfuryl acrylate, 2-(2-ethoxyethoxy)ethyl acrylate, octyl acrylate, decyl acrylate, tridecyl acrylate, isodecyl acrylate, lauryl acrylate, 3,3,5-trimethylcyclohexyl acrylate (TMCHA), dicyclopentenyl acrylate (DCPA), 4-tert-butylcyclohexyl acrylate, cyclohexyl acrylate, caprolactone-modified acrylate, hydroxyethyl acrylate, hydroxybutyl acrylate, polyethylene glycol acrylate, polypropylene glycol acrylate, nonylphenoxy polyethylene glycol acrylate, and nonylphenoxy polypropylene glycol acrylate;

[0441] Monofunctional methacrylate compounds such as 2-phenoxyethyl methacrylate, benzyl methacrylate, isobornyl methacrylate, tetrahydrofurfuryl methacrylate, 2-(2-ethoxyethoxy)ethyl methacrylate, octyl methacrylate, decyl methacrylate, tridecyl methacrylate, isodecyl methacrylate, lauryl methacrylate, 3,3,5-trimethylcyclohexyl methacrylate, dicyclopentenyl methacrylate, 4-tert-butylcyclohexyl methacrylate, cyclohexyl methacrylate, caprolactone-modified methacrylate, hydroxyethyl methacrylate, hydroxybutyl methacrylate, polyethylene glycol methacrylate, polypropylene glycol methacrylate, nonylphenoxy polyethylene glycol methacrylate, and nonylphenoxy polypropylene glycol methacrylate;

[0442] Monofunctional vinyl ether compounds such as n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexyl vinyl ether, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and cyclohexanedimethanol monovinyl ether;

[0443] Monofunctional acrylamide compounds such as acrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide, acryloylmorpholine (ACMO), N-isopropylacrylamide, N-hydroxyethylacrylamide, N-butylacrylamide, N-tert-butylacrylamide, N-(1,1-dimethyl-3-oxobutyl)acrylamide, N-dodecylacrylamide, and N-(butoxymethyl)acrylamide; and

[0444] Monofunctional methacrylamide compounds such as methacrylamide, N-phenyl methacrylamide, N-(methoxymethyl) methacrylamide, N,N-dimethyl methacrylamide, and N-tert-butyl methacrylamide;

[0445] wait.

[0446] Examples of the bifunctional radical polymerizable monomer (hereinafter also referred to as “bifunctional monomer”) include:

[0447] Difunctional acrylate compounds such as hexanediol diacrylate, dipropylene glycol diacrylate, 3-methyl-1,5-pentanediol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, nonanediol diacrylate, decanediol diacrylate, neopentyl glycol diacrylate, polyethylene glycol-modified bisphenol A diacrylate, dioxane ethanol diacrylate, cyclohexanedimethanol diacrylate, tricyclodecane dimethanol diacrylate, etc.;

[0448] 2-(2-vinyloxyethoxy)ethyl acrylate (VEEA);

[0449] Difunctional vinyl compounds such as 1,4-butanediol divinyl ether, cyclohexanedimethanol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether (DVE3), and the like; and

[0450] Difunctional methacrylate compounds such as hexanediol dimethacrylate, dipropylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, neopentyl glycol dimethacrylate, and polyethylene glycol-modified bisphenol A dimethacrylate.

[0451] Examples of free radical polymerizable monomers having three or more functions (hereinafter also referred to as "trifunctional monomers") include trifunctional or more (meth)acrylate compounds such as pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate (DPHA), trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol trimethacrylate, and pentaerythritol tetramethacrylate.

[0452] In addition to the above-mentioned free radical polymerizable monomers, commercially available or industry-known monofunctional or difunctional free radical polymerizable monomers recorded in "Crosslinking Agent Handbook" compiled by Shinzo Yamashita (TAISEISHA, 1981); "UV / EB Curing Handbook (Raw Materials)" compiled by Kiyoshi Kato (1985, Polymer Publishing Association); "Application and Market of UV·EB Curing Technology" compiled by RadTech Japan, page 79 (1989, CMC Publishing Co., Ltd.); "Polyester Resin Handbook" by Eiichiro Ryuyama (1988, NIKKAN KOGYO SHIMBUN, LTD.), etc. can also be used.

[0453] The molecular weight of the radical polymerizable monomer is preferably 100 or more and less than 1,000, more preferably 100 or more and 800 or less, and further preferably 150 or more and 700 or less.

[0454] The free radical polymerizable monomer preferably includes a free radical polymerizable monomer having two or more functions. By including a free radical polymerizable monomer having two or more functions, the content of the monofunctional free radical polymerizable monomer in the ink is relatively reduced or disappears, thereby being able to suppress the phenomenon (so-called migration) of the monomer component from the recorded image to the outside. In particular, from the viewpoint of being applicable to fields that strictly require safety in the substrate, such as food packaging films or cosmetic packaging materials, it is preferred to include a free radical polymerizable monomer having two or more functions.

[0455] Furthermore, for the same reason as described above, it is more preferable that the radical polymerizable monomer contains at least one monomer selected from the group consisting of a monofunctional radical polymerizable monomer, a bifunctional radical polymerizable monomer, and a trifunctional radical polymerizable monomer.

[0456] As the radical polymerizable monomer, it is preferred to select a monomer included in the list of food packaging regulations (EU law, Swiss Ordinance) from the viewpoint of food safety in particular.

[0457] For the same reason as above, it is preferred that a difunctional or higher-functional radical polymerizable monomer is contained as the radical polymerizable monomer, and the content of the difunctional or higher-functional radical polymerizable monomer is 50% by mass or more based on the total content of the radical polymerizable monomers.

[0458] The content of the bifunctional or higher-functional radical polymerizable monomer is more preferably 50 to 90% by mass, further preferably 60 to 80% by mass, and particularly preferably 60 to 75% by mass, based on the total content of the radical polymerizable monomer.

[0459] The content of the radical polymerizable monomer is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, and particularly preferably 80% by mass or more relative to the total mass of the inkjet recording ink. The upper limit can be set to 95% by mass or less, for example. Such an inkjet recording ink is preferably used as a photocurable ink.

[0460] 《Photoradical polymerization initiator》

[0461] The inkjet recording ink of the present invention may contain a photoradical polymerization initiator. When the inkjet recording ink of the present invention contains a radical polymerizable monomer, it preferably further contains a photoradical polymerization initiator.

[0462] Examples of the photoradical polymerization initiator include compounds that generate radicals upon irradiation with light.

[0463] Examples of the photoradical polymerization initiator include (a) carbonyl compounds such as aromatic ketones, (b) acylphosphine oxide compounds, (c) aromatic onium salt compounds, (d) organic peroxides, (e) thio compounds, (f) hexaarylbiimidazole compounds, (g) ketoxime ester compounds, (h) borate compounds, (i) azinium compounds, (j) metallocene compounds, (k) active ester compounds, (i) compounds having a carbon-halogen bond, and (m) alkylamine compounds.

[0464] As the photoradical polymerization initiator, the compounds (a) to (m) described above may be used alone or in combination of two or more.

[0465] The photoradical polymerization initiator is preferably the above-mentioned (a), (b) or (e).

[0466] Preferred examples of (a) the carbonyl compound, (b) the acylphosphine oxide compound and (e) the thio compound include compounds having a benzophenone skeleton or a thioxanthone skeleton as described in "RADIATION CURING IN POLYMER SCIENCE AND TECHNOLOGY", JPFOUASSIER, JFRABEK (1993), pp. 77-117. More preferred examples include α-thiobenzophenone compounds described in Japanese Patent Publication No. 47-006416, benzoin ether compounds described in Japanese Patent Publication No. 47-003981, α-substituted benzoin compounds described in Japanese Patent Publication No. 47-022326, benzoin derivatives described in Japanese Patent Publication No. 47-023664, aromatic acylphosphonates described in Japanese Patent Publication No. 57-030704, dialkoxybenzophenones described in Japanese Patent Publication No. 60-026483, benzoin ethers described in Japanese Patent Publication No. 60-026403, Japanese Patent Publication No. 62-081345, and Japanese Patent Publication No. 62-081345. α-Aminobenzophenones described in Japanese Patent Publication No. 01-034242, U.S. Patent No. 4,318,791, European Patent Publication No. 0284561A1, p-di(dimethylaminobenzoyl)benzene described in Japanese Patent Publication No. 02-211452, thiosubstituted aromatic ketones described in Japanese Patent Publication No. 61-194062, acylphosphine sulfides described in Japanese Patent Publication No. 02-009597, acylphosphines described in Japanese Patent Publication No. 02-009596, thioxanthones described in Japanese Patent Publication No. 63-061950, and coumarins described in Japanese Patent Publication No. 59-042864. Furthermore, the photoradical polymerization initiators described in JP-A-2008-105379 and JP-A-2009-114290 are also preferred.

[0467] Among the photoradical polymerization initiators, more preferred are (a) carbonyl compounds or (b) acylphosphine oxide compounds, and specific examples thereof include bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (e.g., Omnirad 819 manufactured by IGM Resins BV), 2-(dimethylamino)-1-(4-morpholinophenyl)-2-benzyl-1-butanone (e.g., Omnirad 369 manufactured by IGM Resins BV), 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropane-1-one (e.g., Omnirad 907 manufactured by IGM Resins B.V.), 1-hydroxy-cyclohexyl-phenyl-ketone (e.g., Omnirad 184 manufactured by IGM Resins BV), and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (e.g., Omnirad TPO manufactured by IGM Resins BV).

[0468] Among them, the photoradical polymerization initiator is preferably (b) an acylphosphine oxide compound, more preferably a monoacylphosphine oxide compound (particularly preferably 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide) or a bisacylphosphine oxide compound (particularly preferably bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide).

[0469] The content of the photoradical polymerization initiator is preferably 1.0 to 25.0% by mass, more preferably 2.0 to 20.0% by mass, and even more preferably 3.0 to 15.0% by mass relative to the total mass of the inkjet recording ink. Such an inkjet recording ink is preferably used as a photocurable ink.

[0470] Sensitizer

[0471] The inkjet recording ink of the present invention may contain a sensitizer. When the inkjet recording ink of the present invention contains a free radical polymerizable monomer and a photo radical polymerization initiator, it is preferred to further contain a sensitizer. According to this mode, the photocurability can be improved, and in particular, the photocurability when an LED light source is used can be improved.

[0472] The sensitizer is a substance that absorbs specific active energy rays and becomes an electronically excited state. The sensitizer in the electronically excited state contacts the photoradical polymerization initiator to generate electron transfer, energy transfer, heat generation, etc. This promotes the chemical change of the photoradical polymerization initiator, that is, decomposition and generation of free radicals.

[0473] As sensitizer, preferably use pigment sensitizer.As pigment sensitizer, for example can enumerate 4-(dimethylamino) ethyl benzoate (EDB), anthraquinone, 3-acylcoumarin derivatives, terphenyl, phenyl ketone, 3-(aroyl methylene) thiazoline, camphorquinone, eosin, rhodamine, erythrosine, the compound represented by the general formula (i) described in Japanese Unexamined Patent Publication No. 2010-024276 and the compound represented by the general formula (I) described in Japanese Unexamined Patent Publication No. 06-107718.

[0474] When inkjet recording ink is used in the field of food packaging, sufficient curability needs to be ensured from the viewpoint of food safety. Therefore, in the pigment sensitizer, from the viewpoint of food safety and the viewpoint of ensuring better curability by considering the suitability to LED light and the reactivity with the photo-radical polymerization initiator, at least one of a thioxanthone compound and a chromanone compound is preferably included.

[0475] Examples of the thioxanthone compound include thioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dichlorothioxanthone, 2-dodecylthioxanthone, 2,4-diethylthioxanthone, 2,4-dimethylthioxanthone, 1-methoxycarbonylthioxanthone, 2-ethoxycarbonylthioxanthone, 3-(2-methoxyethoxycarbonyl)thioxanthone, 4-butoxycarbonylthioxanthone, 3-butoxycarbonyl-7-methylthioxanthone, 1-cyano-3-chlorothioxanthone, 1-ethoxycarbonyl-3-chlorothioxanthone, 1-ethoxycarbonyl-3-ethoxythioxanthone, 1-ethoxycarbonyl-3-aminothioxanthone, 1-ethoxycarbonyl-3-phenylsulfonylthioxanthone, 3,4-bis[2-(2-methoxyethoxy)ethoxycarbonyl]thioxanthone, 1-ethoxycarbonyl -3-(1-methyl-1-morpholinoethyl)thioxanthone, 2-methyl-6-dimethoxymethylthioxanthone, 2-methyl-6-(1,1-dimethoxybenzyl)thioxanthone, 2-morpholinomethylthioxanthone, 2-methyl-6-morpholinomethylthioxanthone, n-allylthioxanthone-3,4-dicarboxylic imide, n-octylthioxanthone-3,4-dicarboxylic imide, N-(1,1,3,3-tetramethylbutyl)thioxanthone-3,4-dicarboxylic imide, 1-phenoxythioxanthone, 6-ethoxycarbonyl-2-methoxythioxanthone, 6-ethoxycarbonyl-2-methylthioxanthone, thioxanthone-2-polyethylene glycol ester and 2-hydroxy-3-(3,4-dimethyl-9-oxo-9H-thioxanthone-2-yloxy)-N,N,N-trimethyl-1-propaneammonium chloride, etc. Among these, 2,4-diethylthioxanthone, 2-isopropylthioxanthone or 4-isopropylthioxanthone is preferred from the viewpoint of easy availability and curability.

[0476] As the thioxanthone compound, a commercially available product may be used. Examples of the commercially available product include the SPEEDCURE series manufactured by Lambson (for example, SPEEDCURE 7010L, SPEEDCURE CPTX, and SPEEDCURE E ITX).

[0477] As for the thioxanthone compound and the thiochromanone compound, the compounds described in paragraphs 0066 to 0077 of JP-A-2012-046724 and paragraphs 0083 to 0094 of International Publication No. 2020 / 202628 can also be used.

[0478] The molecular weight of the sensitizer is preferably 1,000 or more, more preferably 1,000 to 100,000, and even more preferably 1,000 to 50,000.

[0479] The sensitizer is preferably a thioxanthone compound or thiochromanone compound having a molecular weight of 1,000 or more, more preferably a thioxanthone compound or thiochromanone compound having a molecular weight of 1,000 to 100,000, and still more preferably a thioxanthone compound or thiochromanone compound having a molecular weight of 1,000 to 50,000.

[0480] The content of the sensitizer is preferably 1.0 to 15.0% by mass, more preferably 1.5 to 10.0% by mass, and even more preferably 2.0 to 6.0% by mass, relative to the total mass of the inkjet recording ink.

[0481] 《Polymerization Inhibitors》

[0482] The inkjet recording ink of the present invention may contain a polymerization inhibitor. In particular, when the inkjet recording ink contains the above-mentioned radical polymerizable compound and a photoradical polymerization initiator, it is preferable to further contain a polymerization inhibitor.

[0483] Examples of the polymerization inhibitor include p-methoxyphenol, quinones (e.g., hydroquinone, benzoquinone, and methoxybenzoquinone), phenothiazine, catechols, alkylphenols (e.g., butylhydroxytoluene (BHT)), alkylbisphenols, zinc dimethyldithiocarbamate, copper dimethyldithiocarbamate, copper dibutyldithiocarbamate, copper salicylate, thiodipropionate esters, mercaptobenzimidazole, phosphites, 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO), 2,2,6,6-tetramethyl-4-hydroxypiperidin-1-oxyl (TEMPOL), and tris(N-nitroso-N-phenylhydroxylamine)aluminum salt (also known as cupferroin Al). Among them, the polymerization inhibitor is preferably at least one selected from p-methoxyphenol, catechols, quinones, alkylphenols, TEMPO, TEMPOL and tris(N-nitroso-N-phenylhydroxylamine)aluminum salt, and more preferably at least one selected from p-methoxyphenol, hydroquinone, benzoquinone, BHT, TEMPO, TEMPOL and tris(N-nitroso-N-phenylhydroxylamine)aluminum salt.

[0484] When the inkjet recording ink contains a polymerization inhibitor, the content of the polymerization inhibitor is preferably 0.01 to 2.0% by mass relative to the total mass of the inkjet recording ink.

[0485] Other pigments

[0486] Inkjet recording ink of the present invention can comprise other pigments except above-mentioned specific infrared absorption pigment.As other pigments, there is no particular restriction, and known pigments in the field of inkjet recording ink can be used.From the viewpoint of the invisibility of the infrared absorption image obtained, the content of other pigments is preferably below 0.1 mass % with respect to the gross mass of inkjet recording ink, more preferably below 0.05 mass %.

[0487] 《Other ingredients》

[0488] In the inkjet recording ink of the present invention, other ingredients include anti-fading agents, emulsion stabilizers, penetration enhancers, ultraviolet absorbers, preservatives, mildew inhibitors, pH adjusters, surface tension adjusters, defoamers, viscosity modifiers, dispersion stabilizers, rust inhibitors, chelating agents and other additives. For the above ingredients, the compounds described in paragraphs 0044 to 0050 of Japanese Patent Application Publication No. 2008-144004 can be used.

[0489] 《Preferred embodiments of inkjet recording ink》

[0490] (First method)

[0491] One preferred embodiment (first embodiment) of the inkjet recording ink of the present invention is an embodiment of an aqueous ink containing the specific infrared absorbing dye, water, and an organic solvent having a boiling point of 100° C. or higher.

[0492] In the inkjet recording ink of the first mode, the content of the specific infrared absorbing pigment is preferably 0.1 to 20% by mass relative to the total mass of the inkjet recording ink. The lower limit is preferably 0.2% by mass or more, and more preferably 0.3% by mass or more. The upper limit is preferably 10% by mass or less, and more preferably 5% by mass or less. In addition, the content of water is preferably 50% by mass or more, more preferably 60% by mass or more, and more preferably 70% by mass or more relative to the total mass of the inkjet recording ink. The upper limit of the water content is not particularly limited, as long as it is determined according to the content of other components, but is preferably 99% by mass or less, more preferably 98% by mass or less, and more preferably 95% by mass or less. In addition, the content of the organic solvent having a boiling point of 100°C or more is preferably 1 to 40% by mass, and more preferably 2 to 30% by mass relative to the total mass of the inkjet recording ink.

[0493] The inkjet recording ink of the first embodiment preferably further comprises resin particles. The content of the resin particles is not particularly limited, but is preferably 1 to 20% by mass, more preferably 2 to 12% by mass, and preferably 3 to 10% by mass relative to the total mass of the inkjet recording ink. Furthermore, the resin particles are preferably included in an amount of 60 to 96 parts by mass relative to 100 parts by mass of the total of the specific infrared absorbing pigment and the resin particles.

[0494] The inkjet recording ink of the first embodiment may further contain the above-mentioned materials such as a surfactant, a water-soluble polymer compound, a dispersant, and other pigments.

[0495] (Second method)

[0496] Another preferred embodiment (second embodiment) of the inkjet recording ink of the present invention is an embodiment of a photocurable ink containing the above-mentioned specific infrared absorbing dye, a radical polymerizable monomer, and a photoradical polymerization initiator.

[0497] In the inkjet recording ink of the second mode, the content of the specific infrared absorbing pigment is preferably 0.1 to 20% by mass relative to the total mass of the inkjet recording ink. The lower limit is preferably 0.2% by mass or more, and more preferably 0.3% by mass or more. The upper limit is preferably 10% by mass or less, and more preferably 5% by mass or less. In addition, the content of the free radical polymerizable monomer is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, and particularly preferably 80% by mass or more relative to the total mass of the inkjet recording ink. The upper limit can be set to 95% by mass or less, for example. In addition, the content of the photoradical polymerization initiator is preferably 1.0 to 25.0% by mass relative to the total mass of the inkjet recording ink, more preferably 2.0 to 20.0% by mass, and further preferably 3.0 to 15.0% by mass.

[0498] The inkjet recording ink of the second embodiment preferably further contains a sensitizer. The content of the sensitizer is preferably 1.0 to 15.0% by mass, more preferably 1.5 to 10.0% by mass, and even more preferably 2.0 to 6.0% by mass relative to the total mass of the inkjet recording ink.

[0499] The inkjet recording ink of the second embodiment also preferably further contains a polymerization inhibitor. The content of the polymerization inhibitor is preferably 0.01 to 2.0% by mass relative to the total mass of the inkjet recording ink.

[0500] The inkjet recording ink of the second embodiment may further contain the above-mentioned materials such as a surfactant, a dispersant, and other pigments.

[0501] In the inkjet recording ink of the second embodiment, the water content is preferably 3% by mass or less, more preferably 2% by mass or less, and further preferably 1% by mass or less relative to the total mass of the inkjet recording ink. The inkjet recording ink is preferably a non-aqueous ink that does not substantially contain water.

[0502] In the inkjet recording ink of the second embodiment, the content of the organic solvent is preferably 1% by mass or less, more preferably 0.5% by mass or less, and further preferably 0.1% by mass or less relative to the total mass of the inkjet recording ink. The inkjet recording ink of this embodiment may be a composition that does not contain an organic solvent (i.e., the content of the organic solvent is 0% by mass relative to the total mass of the inkjet recording ink).

[0503] <Method for producing inkjet recording ink>

[0504] As the manufacture method of inkjet recording ink of the present invention, it is not particularly limited, and can be manufactured (prepared) by the manufacture method (preparation method) of known ink. For example, it can be manufactured by the manufacture method of the ink described in writing in Japanese Patent Laid-Open No. 05-148436 Gazette, Japanese Patent Laid-Open No. 05-295312 Gazette, Japanese Patent Laid-Open No. 07-097541 Gazette, Japanese Patent Laid-Open No. 07-082515 Gazette, Japanese Patent Laid-Open No. 07-118584 Gazette, Japanese Patent Laid-Open No. 11-286637 Gazette or Japanese Patent Laid-Open No. 11-286637 Gazette.

[0505] <Inkjet Recording Method>

[0506] The inkjet recording method of the present invention includes the step of forming an infrared absorption image using the inkjet recording ink of the present invention.

[0507] The step of forming an infrared absorption image is a step of applying the inkjet recording ink of the present invention to a substrate by an inkjet method. According to this step, the ink can be selectively applied to the substrate, thereby forming a desired infrared absorption image.

[0508] The substrate for forming the infrared absorption image is not particularly limited as long as it is a substrate capable of forming the infrared absorption image, and examples thereof include paper, cloth, wood, metal plates, plastic films, etc. The paper is not particularly limited, and general printing paper mainly composed of cellulose, such as so-called high-quality paper, coated paper, and coated paper used for general offset printing, or inkjet recording paper can be used without particular limitation.

[0509] As the substrate, an impermeable substrate can also be used. The "impermeability" of the impermeable substrate used in this specification means that the water contained in the ink is absorbed little or not, and specifically, the water absorption amount is 10.0 g / m 2 The following properties.

[0510] The form of the impermeable substrate is not particularly limited, and examples thereof include sheet-like substrates, film-like substrates, etc. From the viewpoint of productivity of printed matter, the impermeable substrate is preferably an impermeable substrate that can be formed into a roll by winding the sheet-like or film-like impermeable substrate.

[0511] Examples of the impermeable substrate include metals (e.g., aluminum foil), plastic films (e.g., polyvinyl chloride resin, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), plastics, glass, etc. Among them, substrates made of thermoplastic resins such as polyvinyl chloride, polyethylene terephthalate, and polypropylene are preferred.

[0512] The non-permeable substrate can be subjected to surface treatment. As surface treatment, corona treatment, plasma treatment, frame treatment, heat treatment, abrasion treatment, light irradiation treatment (UV treatment), flame treatment, etc. can be cited, but are not limited to these. For example, by applying corona treatment to the surface of the non-permeable substrate before the ink is given to form an image, the surface energy of the non-permeable substrate can be increased, and the wetting of the surface of the non-permeable substrate and the adhesion of the ink to the non-permeable substrate can be promoted. Regarding the corona treatment, for example, Corona Master (Shinko Electric & Instrumentation Co., Ltd. system, PS-10S) can be used. Regarding the conditions for the corona treatment, as long as it is appropriately selected according to the type of the non-permeable substrate, the composition of the ink, etc. For example, it can be set to the following treatment conditions.

[0513] ·Processing voltage: 10~15.6kV

[0514] Processing speed: 30~100mm / s

[0515] A visible image may be formed on the above substrate by inkjet method or other known methods.

[0516] The infrared absorption image formed in this step is not particularly limited, but is preferably an infrared absorption image composed of a plurality of element patterns (e.g., a dot pattern, a line pattern, etc.), in other words, an infrared absorption image that is a collection of a plurality of element patterns. The diameter of the dot pattern is preferably 25 μm to 70 μm, more preferably 30 μm to 60 μm.

[0517] The inkjet method is not particularly limited and may be any of the known methods, such as a charge control method that utilizes electrostatic induction force to eject ink, a drop-on-demand inkjet method (pressure pulse method) that utilizes the vibration pressure of a piezoelectric element, an acoustic inkjet method that converts an electrical signal into a sound beam and irradiates the ink to eject the ink using radiation pressure, and a thermal inkjet (BubbleJet (registered trademark)) method that heats the ink to form bubbles and utilizes the generated pressure.

[0518] As the inkjet method, the following method can be particularly effectively used: by using the method described in Japanese Patent Application Laid-Open No. 54-059936, the ink subjected to thermal energy undergoes a rapid volume change, and the ink is ejected from the nozzle by the force generated by the state change.

[0519] In addition, regarding the inkjet method, reference can also be made to the method described in paragraphs 0093 to 0105 of Japanese Patent Application Laid-Open No. 2003-306623.

[0520] As inkjet heads used in the inkjet method, there are a reciprocating method that uses a short-sized column head to record while scanning the head in the width direction of the substrate, and a linear method that uses a row head with recording elements arranged in the entire area corresponding to one side of the substrate.

[0521] In the line method, a pattern can be formed on the entire surface of the substrate by scanning the substrate in a direction intersecting the arrangement direction of the recording elements, and a transport system such as a carriage for scanning a short-sized head is not required.

[0522] Furthermore, since there is no need to perform complicated scanning control on the movement of the carriage and the substrate, only the substrate moves, and thus the recording speed can be increased compared to the reciprocating method.

[0523] The inkjet recording method of this embodiment can be applied to any of them, but is preferably a line type method.

[0524] The amount of ink droplets discharged from the inkjet head is preferably 1 pL (picoliter, the same hereinafter) to 10 pL, and more preferably 1.5 pL to 6 pL, from the viewpoint of obtaining a high-definition pattern.

[0525] The amount of the specific infrared absorbing dye applied per unit area in the infrared absorbing image formed in this step is preferably 0.05 g / m 2 ~1.0g / m 2 , more preferably 0.1 g / m 2 ~0.5g / m 2 .

[0526] In the inkjet recording method of the present invention, the inkjet recording ink applied to the substrate may be irradiated with light. When a photocurable ink is used as the inkjet recording ink, it is preferred to irradiate the inkjet recording ink applied to the substrate with light to form an infrared absorption image.

[0527] As a light source used for light irradiation, a light emitting diode etc. are mentioned.

[0528] Examples of the light irradiated by the light source include ultraviolet (UV) light and visible light, and UV light is preferred.

[0529] The peak wavelength of the irradiation light also depends on the absorption characteristics of the radical polymerization initiator and the dye sensitizer, but is preferably 200nm to 600nm, more preferably 300nm to 450nm, further preferably 320nm to 42Ohm, and particularly preferably ultraviolet light with a peak wavelength of 340nm to 400nm.

[0530] As the light emitting diode (LED) used as a light source, ultraviolet LEDs and the like can be cited. For example, a purple LED manufactured by Nichia Corporation, whose main emission spectrum has a wavelength between 365nm and 420nm, can be cited. In addition, an LED described in the specification of U.S. Patent No. 6,084,250, which can release active radiation centered between 300nm and 370nm, can also be cited. In this specification, a particularly preferred active radiation source is a UV-LED, and a UV-LED having a peak wavelength in the wavelength region of 340nm to 400nm is particularly preferred. For example, an LED having a peak wavelength of 355nm, 365nm, 385nm, 395nm or 405nm is more preferred, and an LED having a peak wavelength of 355nm, 365nm, 385nm, 395nm or 405nm is particularly preferred.

[0531] The maximum illuminance of the LED on the substrate is preferably 10 mW / cm 2 ~2000mW / cm 2 , more preferably 20 mW / cm 2 ~1000mW / cm 2 , more preferably 50mW / cm 2 ~800mW / cm 2 .

[0532] The inkjet recording method of the present invention may include a step of heating the formed infrared absorption image. In the heating step, drying may also be performed simultaneously.

[0533] As a mechanism for heating the infrared absorption image, there can be mentioned a known heating mechanism such as a heater, a known air blowing mechanism such as a dryer, and a combination of these.

[0534] As methods for heating the infrared absorbing image, for example, there can be cited a method of applying heat from the side of the recording medium (substrate) opposite to the image forming surface using a heater, a method of blowing warm air or hot air toward the image forming surface of the recording medium, a method of applying heat from the image forming surface of the recording medium or the side opposite to the image forming surface using an infrared heater, a method combining a plurality of these, and the like.

[0535] The heating temperature of the infrared absorption image is preferably 60° C. or higher, more preferably 65° C. or higher, and particularly preferably 70° C. or higher. The upper limit of the heating temperature is not particularly limited, but as an upper limit, for example, it is preferably 150° C. or lower. The heating time of the infrared absorption image is not particularly limited, but is preferably 1 second to 300 seconds, and more preferably 1 second to 30 seconds.

[0536] <Printed items>

[0537] The printed matter of the present invention comprises a substrate and an infrared absorption image obtained using the inkjet recording ink of the present invention.

[0538] The printed matter of the present invention is preferably a printed matter obtained by the above-mentioned inkjet recording method.

[0539] The substrate in the printed matter of the present invention is the same as the substrate in the above-mentioned ink jet recording method, and the preferred aspects are also the same.

[0540] The infrared absorption image in the printed matter of the present invention is obtained using the above-mentioned inkjet recording ink of the present invention.

[0541] The maximum absorption wavelength of the infrared absorption image in the printed matter of the present invention is preferably within the wavelength range of 700 nm to 1800 nm, more preferably within the wavelength range of 800 nm to 1600 nm, and further preferably within the wavelength range of 900 nm to 1600 nm.

[0542] From the viewpoint of invisibility and readability of the infrared absorption image, in the infrared absorption image in the printed matter of the present invention, the maximum absorption wavelength within the wavelength range of 400 to 1800 nm preferably exists within the wavelength range of 700 to 1800 nm.

[0543] From the viewpoint of invisibility of the infrared absorption image, the optical density at a wavelength of 450 nm in the infrared absorption image in the printed matter is preferably 1 / 5 or less of the optical density at the maximum absorption wavelength. Furthermore, from the viewpoint of readability, the optical density at the maximum absorption wavelength of the infrared absorption image is preferably 0.1 or more, more preferably 0.3 or more, and even more preferably 0.5 or more.

[0544] In the infrared absorption image in the printed matter, the content per unit area of ​​the specific infrared absorption pigment is preferably 0.05 g / m 2 ~1.0g / m 2 , more preferably 0.1 g / m 2 ~0.5g / m 2 .

[0545] Example

[0546] The present invention will be described in more detail below with reference to Examples. The materials, usage amounts, ratios, treatment contents, treatment procedures, etc. shown in the following Examples can be appropriately changed without departing from the spirit of the present invention.

[0547] <Test Example 1>

[0548] (Example 1) Preparation of Ink 1

[0549] 〔Preparation of pigment dispersion〕

[0550] A mixture of the components described below was dispersed for 2 hours using a paint shaker, thereby obtaining a solid dispersion of Compound 001.

[0551] -composition-

[0552] · Demol SN-B (manufactured by Kao Corporation) ... 0.5 parts by mass

[0553] Compound 001…2.0 parts by mass

[0554] Ultrapure water…97.5 parts by mass

[0555] In addition, Compound 001 is Compound 001 shown in the specific examples of the above-mentioned specific infrared absorbing dye.

[0556] [Preparation of ink]

[0557] A mixture of the components having the following composition was stirred at 35° C. for 1 hour. Then, the mixture was filtered under reduced pressure using a microfilter having an average pore size of 5 μm to obtain an inkjet recording ink (ink 1) of Example 1.

[0558] -composition-

[0559] ·The above pigment dispersion…50 parts by mass

[0560] · Propylene glycol…20 parts by mass

[0561] ·OLFINE E1010 (Nissin Chemical Co., Ltd., acetylene glycol surfactant) ... 1 part by mass

[0562] ·Triethanolamine…0.2 parts by mass

[0563] Ultrapure water (resistance value 18 MΩ·cm or more) ... the total amount of the composition to make 100 parts by mass

[0564] (Example 2) Preparation of Ink 2

[0565] Inkjet recording ink (Ink 2) of Example 2 was obtained in the same manner as Ink 1 except that Compound 001 was replaced with Compound 002. Compound 002 was Compound 002 listed in the above-mentioned specific examples of the specific infrared absorbing dye.

[0566] (Example 3) Preparation of Ink 3

[0567] Inkjet recording ink (Ink 3) of Example 3 was obtained in the same manner as Ink 1 except that Compound 001 was replaced with Compound 003. Compound 003 is Compound 003 listed in the above-mentioned specific examples of the specific infrared absorbing dye.

[0568] (Example 4) Preparation of Ink 4

[0569] In the preparation of ink 1, except that compound 001 was changed to compound 033, the same procedure as in the preparation of ink 1 was carried out to obtain an inkjet recording ink of Example 4 (ink 4).

[0570] (Example 5) Preparation of Ink 5

[0571] In the preparation of ink 1, except that compound 001 was changed to compound 045, the same procedure as in the preparation of ink 1 was carried out to obtain an inkjet recording ink of Example 5 (ink 5).

[0572] (Comparative Example 1) Preparation of Comparative Ink 1

[0573] In the preparation of ink 1, an inkjet recording ink of Comparative Example 1 (Comparative ink 1) was obtained in the same manner as in the preparation of ink 1, except that compound 001 was changed to comparative compound 1 having the following structure.

[0574] [Chemical formula 27]

[0575]

[0576] (Production of printed matter)

[0577] [Production of Print A]

[0578] The above-mentioned inks 1 to 5 or comparative ink 1 were loaded into the ink tank of an inkjet recording device (manufactured by FUJIFILM Di matix, Inc., DMP-2831), and a solid image was printed on OK Top Coat paper (manufactured by OJI PAPER CO., LTD.) using an inkjet head, thereby obtaining prints A-1 to A-5 or comparative print A-1, respectively.

[0579] In addition, a “solid image” refers to a surface image formed by applying ink at a dot rate of 100%.

[0580] [Production of Printed Material B]

[0581] The above inks 1 to 5 or comparative ink 1 were loaded into the ink tank of an inkjet recording device (DMP-2831 manufactured by FUJIFILM Dimatix, Inc.), and the inkjet head of the inkjet recording device ejected the above inks onto a 5.4 mm×5.4 mm square area of ​​OK TopCoat paper (manufactured by OJIPAPERCO., LTD.) to form an infrared absorption pattern consisting of a plurality of dot patterns, thereby obtaining a printed matter. The infrared absorption pattern formed in the above process will be described in detail below.

[0582] Assume that the square area of ​​5.4 mm×5.4 mm on the surface coated with the treatment liquid is divided into 9 pieces in the longitudinal direction and 9 pieces in the transverse direction, and the total number of first grids is 81. Furthermore, assume that each first grid is divided into 3 pieces in the longitudinal direction and 3 pieces in the transverse direction, and each first grid has 9 second grids. In the square area of ​​5.4 mm×5.4 mm, the number of second grids is 729 (=81×9).

[0583] A dot pattern having a diameter of 50 μm is formed in the center of any second grid among the nine second grids included in one first grid. The number of dot patterns in one first grid is set to one to nine.

[0584] Figure 1 It is a schematic plan view showing an example of the arrangement of dot patterns in one first grid.

[0585] like Figure 1 As shown, in this example, among the nine second grids 12 in the first grid 11, the dot pattern 14 is formed in the center of each of seven second grids 12. Figure 1 In the example, only a portion of the second grid is assigned the symbol "12", and only a portion of the dot pattern is assigned the symbol "14".

[0586] In a square region of 5.4 mm×5.4 mm, the number of dot patterns (that is, the arrangement of the dot patterns) is made different for each first grid.

[0587] The infrared absorption pattern formed in this embodiment is a collection of the above-mentioned dot patterns.

[0588] [Evaluation of invisibility]

[0589] The invisibility of the printed matter A-1 to A-5 and the comparative printed matter A-1 was evaluated. Regarding the invisibility, the optical density at a wavelength of 450 nm and the optical density at the maximum absorption wavelength were measured using a spectrophotometer UV-3100PC (manufactured by Shimadzu Corporation) equipped with a large integrating sphere attachment LISR-3100 (manufactured by Shimadzu Corporation) with a diameter of 150 mm, and the following evaluation criteria were used for determination. The results are recorded in the table.

[0590] -Invisibility Evaluation Criteria-

[0591] A: "Optical density at a wavelength of 450 nm / optical density at the maximum absorption wavelength" is 1 / 5 (0.2) or less.

[0592] B: "Optical density at a wavelength of 450 nm / optical density at the maximum absorption wavelength" exceeds 1 / 5 (0.2).

[0593] [Evaluation of readability]

[0594] The infrared absorption pattern formed in the above was read using an infrared reading device "0.8 mm Height Flat Top Infrared LED" (manufactured by EVERLIGHT ELECTRONICS CO., LTD.), and the readability of the infrared absorption pattern was evaluated according to the following evaluation criteria.

[0595] -Evaluation criteria for readability-

[0596] A: If you place the infrared reader on the infrared absorption pattern, a reading sound will sound within 3 seconds, confirming that the infrared absorption pattern has been read.

[0597] B: When the infrared reader is placed on the infrared absorption pattern, a reading sound is heard within 10 seconds and more than 3 seconds, confirming that the infrared absorption pattern has been read.

[0598] C: Even when the infrared reader is placed on the infrared absorption pattern, no reading sound is heard and reading is not confirmed.

[0599] [Evaluation of dispersibility]

[0600] Dispersion method 1 (simple dispersion process)

[0601] A paint shaker was used to perform dispersion for 2 hours to obtain a solid dispersion (pigment dispersion) of each compound.

[0602] Dispersion method 2 (cumbersome dispersion processing)

[0603] Dispersion was performed for 5 hours using an AIGA electric mill to obtain a solid dispersion (pigment dispersion) of each compound.

[0604] Each ink was prepared using the solid dispersion (pigment dispersion) prepared by the above-mentioned dispersion method 1 and dispersion method 2, and the above-mentioned ink was loaded into the ink tank of an inkjet recording device (DMP-2831 manufactured by FUJIFILM Dimatix, Inc.), and the ink ejection property was evaluated by the following method as an indicator of the ease of dispersion.

[0605] [Evaluation of ink ejection properties]

[0606] When the ink was ejected from the inkjet head, the ink ejection portion of the inkjet head was visually observed, and the ink ejection properties were evaluated according to the following evaluation criteria.

[0607] Hereinafter, “the ratio (%) of the number of non-ejection nozzles” means the ratio (%) of the number of non-ejection nozzles to the total number of nozzles.

[0608] -Evaluation criteria for ink ejection properties-

[0609] 1: The ratio of non-ejecting nozzles is less than 10%.

[0610] 2: The ratio of the number of non-ejecting nozzles is 10% or more.

[0611] -Evaluation criteria for ease of dispersion-

[0612] A: Ink ejection property was 1 regardless of which dispersing method was used.

[0613] B: The ink ejection property was 1 by any dispersion method.

[0614] C: The ink ejection property was 2 by any dispersion method.

[0615] 〔Evaluation of storage stability〕

[0616] The ink (25 g) was placed in a 30 mL polyethylene bottle and capped, and placed in a thermostatic chamber (25° C.) for 1 week. The viscosity of the ink was measured before and after the placement, and the viscosity increase rate (%) due to the placement was calculated (i.e., the ratio of the viscosity after placement to the viscosity before placement; %), and the storage stability of the ink was evaluated according to the following evaluation criteria.

[0617] The viscosity of the ink was measured at a liquid temperature of 25° C. using VISCOMETER RE-85L (manufactured by TOKI SANGYO CO., LTD.) as a viscometer.

[0618] -Evaluation criteria for storage stability-

[0619] A: The rate of increase in viscosity after standing at 25°C for one week is less than 5%.

[0620] B: The rate of increase in viscosity after leaving the sample at 25° C. for one week is 5% or more and less than 10%.

[0621] C: The rate of increase in viscosity after leaving the sample at 25° C. for one week is 10% or more.

[0622] D: Precipitation occurred due to storage at 25°C for one week.

[0623] [Table 1]

[0624] Invisibility Readability Ease of dispersion Storage stability Example 1 A A A A Example 2 A A A A Example 3 A A A A Example 4 A A A A Example 5 A A A A Comparative Example 1 B C C C

[0625] As shown in the above table, the examples were excellent in storage stability and also excellent in readability and ease of dispersibility compared to the comparative examples.

[0626] <Test Example 2>

[0627] (Example 101) Preparation of Ink 101

[0628] [Preparation of dispersion A]

[0629] 2 parts by mass of Compound 001 were added to 98 parts by mass of ultrapure water and dispersed for 3 hours using a bead mill to obtain a dispersion A. Compound 001 is Compound 001 shown in the above-mentioned specific examples of the specific infrared absorbing dye.

[0630] [Preparation of resin particles A-1]

[0631] Methyl ethyl ketone (540.0 g) was placed in a three-necked flask equipped with a mechanical stirrer, a thermometer, a reflux cooling tube, and a nitrogen inlet tube, and the temperature was raised to 75°C. While the temperature in the reaction container was maintained at 75°C, a mixed solution consisting of methyl methacrylate (108 g), isobornyl methacrylate (388.8 g), methacrylic acid (43.2 g), methyl ethyl ketone (108 g), and "V-601" (manufactured by FUJIFILM Wako Pure Chemical Corporation) (2.1 g) was added dropwise at a constant rate in 2 hours. After the addition was completed, a solution consisting of "V-601" (1.15 g) and methyl ethyl ketone (15.0 g) was added, and stirred at 75°C for 2 hours. Furthermore, a solution consisting of "V-601" (0.54 g) and methyl ethyl ketone (15.0 g) was added, and stirred at 75°C for 2 hours. Then, the temperature was raised to 85° C. and stirring was continued for 2 hours to obtain a resin solution of a copolymer of methyl methacrylate / isobornyl methacrylate / methacrylic acid (=20 / 72 / 8 [mass ratio]).

[0632] The obtained copolymer had a weight average molecular weight (Mw) of 60,000, an acid value of 54.2 mgKOH / g, and a glass transition temperature of 124°C.

[0633] Next, the resin solution (588.2 g) was weighed, isopropanol (165 g) and 1 mol / L sodium hydroxide aqueous solution (120.8 ml) were added, and the temperature in the reaction container was raised to 80°C. Next, distilled water (718 g) was added dropwise at a rate of 20 ml / min to disperse the mixture in water. Then, the temperature in the reaction container was maintained at 80°C for 2 hours, 85°C for 2 hours, and 90°C for 2 hours under atmospheric pressure to distill off the solvent. Furthermore, the reaction container was decompressed to distill off isopropanol, methyl ethyl ketone, and distilled water to obtain an aqueous dispersion of resin particles A-1 as polymer particles (solid content 25% by mass).

[0634] [Preparation of ink 101]

[0635] 25 parts by mass of dispersion A, 20 parts by mass of propylene glycol (manufactured by FUJIFILM Wako Pure Chemical Corporation) as a water-soluble organic solvent, 1 part by mass of OLFINE E1010 (manufactured by Nissin Chemical Co., Ltd.) as a surfactant, and 16 parts by mass of an aqueous dispersion of resin particles A-1 were mixed, adjusted with ion-exchanged water so that the total weight became 100 parts by mass, stirred for 1 hour, and then filtered with a filter having a mesh size of 5 μm to obtain an inkjet recording ink (ink 101) of Example 101.

[0636] [Evaluation of wear resistance]

[0637] The ink 101 was filled into the ink cartridge attached to the inkjet recording device (FUJIFILM DMP-2831), and a 10% dot image was made on a coated paper (OK Top Coat) under the conditions of 600 dpi (dots per inch) and 10 pl per dot. The image was then dried with warm air at 100°C for 1 minute to obtain an infrared absorption image. The obtained infrared absorption image was subjected to a friction test and evaluated in five stages from A to E according to the following evaluation criteria. The evaluation was performed by visual observation and observation with an infrared microscope (a microscope with a portable digital color measurement function, HandyScope, manufactured by Spectra Co-op, with an infrared light source wavelength of 783 nm).

[0638] Regarding the friction test, the 2 The weight was increased by slowly moving a paperweight wrapped with coated paper back and forth twice.

[0639] -Evaluation Criteria-

[0640] A: After the friction test, there are almost no scratches on the surface of the infrared absorption image.

[0641] B: After the rubbing test, there were slight scratches on the surface of the infrared absorption image, but the portion completely scraped off was less than 10%.

[0642] C: After the rubbing test, there is a region where the infrared absorption image is scratched, and the area of ​​the region is 10% or more and less than 30% of the entire image.

[0643] D: After the rubbing test, there is a region where the infrared absorption image is scratched, and the area of ​​the region is 30% or more and less than 50% of the entire image.

[0644] E: After the rubbing test, there is a region where the infrared absorption image is scratched, and the area of ​​the region accounts for 50% or more of the entire image.

[0645] The abrasion resistance of ink 101 is B.

[0646] 〔Evaluation of storage stability〕

[0647] The storage stability of the ink 101 was evaluated by the same method as in Test Example 1. As a result, the storage stability of the ink 101 was rated A.

[0648] <Test Example 3>

[0649] (Examples 201 to 203, Comparative Example 201) Preparation of Inks 201 to 203, Comparative Ink 201

[0650] 〔Preparation of pigment dispersion〕

[0651] A mixture of the components having the following composition was dispersed for 3 hours using a bead mill to obtain a pigment dispersion.

[0652] [Table 2]

[0653]

[0654] [Preparation of ink]

[0655] A mixture of the components having the following compositions was mixed and stirred to obtain inkjet recording inks of Examples 201 to 203 and Comparative Example 1 (Inks 201 to 203, Comparative Ink 201).

[0656] [Table 3]

[0657]

[0658] The abbreviations of the materials listed in the above table are as follows.

[0659] Compound 007 and Compound 018 are Compound 007 and Compound 018 shown in the above-mentioned specific examples of the specific infrared absorbing dye.

[0660] Comparative compound 1: the above comparative compound

[0661] Dispersant A: Solsperse 32000 (manufactured by Lubrizol; a dispersant having no aromatic group)

[0662] Monomer A: 4-HBA (hydroxybutyl acrylate, manufactured by OSAKA ORGANIC CHEMICAL INDUSTRY LTD., monofunctional free radical polymerizable monomer)

[0663] Monomer B: VISCOAT #200 (cyclic trimethylolpropane formal acrylate, manufactured by OSAKA ORGANIC CHEMICAL INDUSTRY LTD., monofunctional free radical polymerizable monomer)

[0664] Monomer C: SR339A (2-phenoxyethyl acrylate), manufactured by Sartomer (monofunctional free radical polymerizable monomer)

[0665] Monomer E: SR341 (3-methyl-1,5-pentanediol diacrylate, manufactured by Sartomer, a multifunctional radical polymerizable monomer)

[0666] Monomer F: DVE-3 (triethylene glycol divinyl ether, manufactured by BASF, a multifunctional free radical polymerizable monomer)

[0667] Initiator A: Omnirad 819 (manufactured by IGM Resins BV, photoradical polymerization initiator)

[0668] Initiator B: Omnirad 184 (manufactured by IGM Resins BV, photoradical polymerization initiator)

[0669] Initiator C: Omnirad TPO (manufactured by IGM Resins BV, photoradical polymerization initiator)

[0670] Sensitizer A: SPEEDCURE 7010L (manufactured by Lambson, molecular weight 1000-2000; thioxanthone compound, pigment sensitizer)

[0671] Sensitizer B: 2-isopropylthioxanthone (molecular weight 254, thioxanthone compound, pigment sensitizer)

[0672] Inhibitor A: FLORSTAB UV12 (tris(N-nitroso-N-phenylhydroxylamine) aluminum salt), manufactured by Kroma Chem Ltd., nitroso-based inhibitor)

[0673] Surfactant A: BYK307 (manufactured by BYK Co., LTD)

[0674] [Production of printed matter]

[0675] The inks 201 to 203 or the comparative ink 201 were filled into the ink cartridge attached to the inkjet recording device (FUJIFILM DMP-2831), and solid images and dot pattern images were printed on coated paper (OK Top Coat, manufactured by Oji Paper Co., Ltd.) at 600 dpi (dots per inch) and 10 pl (picoliter) / dot. Then, a 385 nm UV-LED irradiator (manufactured by CCS) was used as an exposure device, and the exposure energy was 1000 mJ / cm 2 The printed matter is obtained by irradiating the printed matter under exposure conditions to cure the printed matter to form an infrared absorption image.

[0676] 〔Performance Evaluation〕

[0677] Invisibility, readability, dispersibility, and storage stability were evaluated by the same method as in Test Example 1. The results are shown in the following table.

[0678] [Table 4]

[0679] Embodiment 201 Embodiment 202 Embodiment 203 Comparative Example 201 Invisibility A A A B Readability A B A C Ease of dispersion A B A C Storage stability A A A C

[0680] As shown in the above table, the examples were excellent in storage stability and also excellent in readability and ease of dispersibility compared to the comparative examples.

[0681] Explanation of symbols

[0682] 11-1st grid, 12-2nd grid, 14-dot pattern.

Claims

1. An inkjet recording ink comprising at least one infrared absorbing pigment A selected from a pigment A1 represented by formula (1) and a pigment multimer A2 containing two or more pigment structures derived from the pigment A1 in one molecule, In formula (1), L 101 Represents -P(=O)(R L101 )-、-P(=S)(R L102 )-、-Si(R L103 )(R L104 )-、-B(R L105 )-, -S(=O)2- or -S(=O)-, R L101 ~R L105 Each independently represents a hydrogen atom or a substituent, R L103 With R L104 are optionally bonded to form a ring, X 101 ~X 103 Each independently represents a nitrogen atom or -CR X101 -, R X1014 represents a hydrogen atom or a substituent, L 102 and L 103 Each independently represents a sulfur atom or -X 104 =X 105 -, X 104 and X 105 Each independently represents a nitrogen atom or -CR X102 -, R X102 represents a hydrogen atom or a substituent, Ar 101 and Ar 102 Respectively independently represent -(CR Ar101 =CR Ar102 ) n101 -, an arylene group, a heterocyclic group or a group formed by combining two or more of these groups, R Ar101 and R Ar102 Each independently represents a hydrogen atom or a substituent, n101 represents an integer of 1 to 3, Y 101 and Y 102 Represents -OR independently Y101 、-NR Y102 R Y103 or -SR Y104 , R Y101 ~R Y104 Each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heteroaryl group, and R Y102 With R Y103 Optionally bonded via a single bond or a divalent linking group to form a ring, Ar 101 With X 101 Optionally bonded via a single bond or a divalent linking group to form a 5-membered ring or a 6-membered ring, Ar 101 With Y 101 Optionally bonded via a single bond or a divalent linking group to form a 5-membered ring or a 6-membered ring, Ar 102 With X 102 Optionally bonded via a single bond or a divalent linking group to form a 5-membered ring or a 6-membered ring, Ar 102 With Y 102 Optionally bonded via a single bond or a divalent linking group to form a 5-membered ring or a 6-membered ring, Z 1 represents the counter ion, p1 represents an integer from 0 to 5, q1 represents an integer from 1 to 5.

2. The inkjet recording ink according to claim 1, wherein X in the formula (1) 103 For-CR X101 -, R X101 is a hydrogen atom or a substituent, L 102 and L 103 are sulfur atoms respectively.

3. The inkjet recording ink according to claim 1, wherein X in the formula (1) 103 For-CR X101 -, R X101 is a hydrogen atom or a substituent, L 102 and L 103 are sulfur atoms, L 101 =P(=O)(R L101 )-,R L101 is a hydrogen atom or a substituent.

4. The inkjet recording ink according to claim 1, wherein X in the formula (1) 103 For-CR X101 -, R X101 is a hydrogen atom or a substituent, L 102 and L 103 are sulfur atoms, L 101 =P(=O)(R L101 )-,R L101 is a hydrogen atom or a substituent, Y 101 and Y 102 Each independently is -NR Y102 R Y103 , R Y102 and R Y103 are independently a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heteroaryl group, R Y102 With R Y103 Optionally, they are bonded via a single bond or a divalent linking group to form a ring.

5. The inkjet recording ink according to claim 1, wherein X in the formula (1) 103 For-CR X101 -, R X101 is a hydrogen atom or a substituent, L 102 and L 103 are sulfur atoms, L 101 -Si(R L103 )(R L104 )- or -S(=O)-, R L103 and R L104 are each independently a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heteroaryl group, Y 101 and Y 102 Each independently is -NR Y102 R Y103 , R Y102 and R Y103 are independently a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heteroaryl group, R Y102 With R Y103 Optionally, they are bonded via a single bond or a divalent linking group to form a ring.

6. The inkjet recording ink according to any one of claims 1 to 5, wherein When the inkjet recording ink is dried, the maximum absorption wavelength of the dried product exists in the wavelength range of 700 to 1800 nm. 7 . The inkjet recording ink according to claim 1 , comprising water and an organic solvent having a boiling point of 100° C. or higher at 101.325 kPa. 8 . The inkjet recording ink according to claim 7 , further comprising resin particles. 9 . The inkjet recording ink according to claim 1 , comprising a radical polymerizable monomer and a photoradical polymerization initiator. 10 . The inkjet recording ink according to claim 9 , further comprising a sensitizer. 11 . The inkjet recording ink according to claim 9 , which is a photocurable ink. 12 . An inkjet recording method comprising the step of forming an infrared absorption image using the inkjet recording ink according to claim 1 .

13. A printed matter, comprising: substrate; and An infrared absorption image obtained using the inkjet recording ink according to any one of claims 1 to 5.

Images